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Robotics, IEEE Transactions on

Issue 4 • Date Aug. 2007

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Displaying Results 1 - 25 of 26
  • Table of contents

    Page(s): C1
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  • IEEE Transactions on Robotics publication information

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  • A Geometric Theory for Analysis and Synthesis of Sub-6 DoF Parallel Manipulators

    Page(s): 625 - 649
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1284 KB) |  | HTML iconHTML  

    Mechanism synthesis is mostly dependent on the designer's experience and intuition and is difficult to automate. This paper aims to develop a rigorous and precise geometric theory for analysis and synthesis of sub-6 DoF (or lower mobility) parallel manipulators. Using Lie subgroups and submanifolds of the special Euclidean group SE(3), we first develop a unified framework for modelling commonly used primitive joints and task spaces. We provide a mathematically rigorous definition of the notion of motion type using conjugacy classes. Then, we introduce a new structure for subchains of parallel manipulators using the product of two subgroups of SE(3) and discuss its realization in terms of the primitive joints. We propose the notion of quotient manipulators that substantially enriches the topologies of serial manipulators. Finally, we present a general procedure for specifying the subchain structures given the desired motion type of a parallel manipulator. The parallel mechanism synthesis problem is thus solved using the realization techniques developed for serial manipulators. Generality of the theory is demonstrated by systematically generating a large class of feasible topologies for (parallel or serial) mechanisms with a desired motion type of either a Lie subgroup or a submanifold. View full abstract»

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  • Port-Based Modeling of a Flexible Link

    Page(s): 650 - 660
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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (731 KB) |  | HTML iconHTML  

    In this paper, a simple way to model flexible robotic links is presented. This is different from classical approaches and from the Euler-Bernoulli or Timoshenko theory, in that the proposed model is able to describe large deflections in 3D space and does not rely on any finite-dimensional approximation (e.g., modal approximation). The model has been formulated within the port Hamiltonian formalism because intuitive considerations on the geometric behavior of the elastic link naturally define a Stokes-Dirac structure, the kernel of a port Hamiltonian system. Moreover, port Hamiltonian systems can be easily interconnected, thus allowing the description of complex systems as a composition of parts in an object-oriented way. By combining rigid bodies, springs, dampers, joints and, finally, flexible links, it is virtually possible to model and mathematically describe whatever complex mechanical structure formed by beams. In order to demonstrate the dynamical properties of the model and how complex mechanisms can be obtained by port interconnection, simulations of 1-DoF and 2-DoF serial manipulators and of a 2-DoF flexible closed kinematic chain are presented. View full abstract»

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  • The Design and Analysis of an Efficient Local Algorithm for Coverage and Exploration Based on Sensor Network Deployment

    Page(s): 661 - 675
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1460 KB) |  | HTML iconHTML  

    We present the design and theoretical analysis of a novel algorithm termed least recently visited (LRV). LRV efficiently and simultaneously solves the problems of coverage, exploration, and sensor network deployment. The basic premise behind the algorithm is that a robot carries network nodes as a payload, and in the process of moving around, emplaces the nodes into the environment based on certain local criteria. In turn, the nodes emit navigation directions for the robot as it goes by. Nodes recommend directions least recently visited by the robot, hence, the name LRV. We formally establish the following two properties: 1) LRV is complete on graphs and 2) LRV is optimal on trees. We present experimental conjectures for LRV on regular square and cube lattice graphs and compare its performance empirically to other graph exploration algorithms. We study the effects of the order of the exploration and show on a square lattice that with an appropriately chosen order, LRV performs optimally. Finally, we discuss the implementation of LRV in simulation and in real hardware. View full abstract»

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  • Stochastic Event Capture Using Mobile Sensors Subject to a Quality Metric

    Page(s): 676 - 692
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (426 KB) |  | HTML iconHTML  

    Mobile sensors cover more area over a fixed period of time than do the same number of stationary sensors. However, the quality of coverage (QoC) achieved by mobile sensors depends on the velocity, mobility pattern, number of mobile sensors deployed, and the dynamics of the phenomenon being sensed. The gains attained by mobile sensors over static sensors and the optimal motion strategies for mobile sensors are not well understood. In this paper, we consider the following event capture problem: the events of interest arrive at certain points in the sensor field and disappear according to known arrival and departure time distributions. An event is said to be captured if it is sensed by one of the mobile sensors before it fades away. We analyze how the QoC scales with velocity, path, and number of mobile sensors. We characterize cases where the deployment of mobile sensors has no advantage over static sensors, and find the optimal velocity pattern that a mobile sensor should adopt. We also present algorithms for two motion planning problems: 1) for a single sensor, what is the sensor trajectory and the minimum speed required to satisfy a bound on the event loss probability and 2) for sensors with fixed speed, what is the minimum number of sensors required to satisfy a bound on the event loss probability. When the robots are restricted to move along a line or a closed curve, our algorithms return the optimal velocity for the minimum velocity problem. For the minimum sensor problem, the number of sensors used is within a factor of 2 of the optimal solution. For the case where the events occur at arbitrary points on a plane, we present heuristic algorithms for the aforementioned motion planning problems and bound their performance with respect to the optimal. View full abstract»

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  • Distributed Coordination Control of Multiagent Systems While Preserving Connectedness

    Page(s): 693 - 703
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB) |  | HTML iconHTML  

    This paper addresses the connectedness issue in multiagent coordination, i.e., the problem of ensuring that a group of mobile agents stays connected while achieving some performance objective. In particular, we study the rendezvous and the formation control problems over dynamic interaction graphs, and by adding appropriate weights to the edges in the graphs, we guarantee that the graphs stay connected. View full abstract»

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  • Localization With Limited Sensing

    Page(s): 704 - 716
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (643 KB) |  | HTML iconHTML  

    Localization is a fundamental problem for many kinds of mobile robots. Sensor systems of varying ability have been proposed and successfully used to solve the problem. This paper probes the lower limits of this range by describing three extremely simple robot models and addresses the active localization problem for each. The robot, whose configuration is composed of its position and orientation, moves in a fully-known, simply connected polygonal environment. We pose the localization task as a planning problem in the robot's information space, which encapsulates the uncertainty in the robot's configuration. We consider robots equipped with: 1) angular and linear odometers; 2) a compass and contact sensor and; 3) an angular odometer and contact sensor. We present localization algorithms for models 1 and 2 and show that no algorithm exists for model 3. An implementation with simulation examples is presented. View full abstract»

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  • SC-KF Mobile Robot Localization: A Stochastic Cloning Kalman Filter for Processing Relative-State Measurements

    Page(s): 717 - 730
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (505 KB) |  | HTML iconHTML  

    This paper presents a new method to optimally combine motion measurements provided by proprioceptive sensors, with relative-state estimates inferred from feature-based matching. Two key challenges arise in such pose tracking problems: 1) the displacement estimates relate the state of the robot at two different time instants and 2) the same exteroceptive measurements are often used for computing consecutive displacement estimates, a process that renders the errors in these correlated. We present a novel stochastic cloning Kalman filtering (SC-KF) estimation algorithm that successfully addresses these challenges, while still allowing for efficient calculation of the filter gains and covariances. The proposed algorithm is not intended to compete with simultaneous localization and mapping (SLAM) approaches. Instead, it can be merged with any extended-Kalman- filter-based SLAM algorithm to increase its precision. In this respect, the SC-KF provides a robust framework for leveraging additional motion information extracted from dense point features that most SLAM algorithms do not treat as landmarks. Extensive experimental and simulation results are presented to verify the validity of the proposed method and to demonstrate that its performance is superior to that of alternative position-tracking approaches. View full abstract»

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  • Closing the Loop With Graphical SLAM

    Page(s): 731 - 741
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (566 KB) |  | HTML iconHTML  

    The problem of simultaneous localization and mapping (SLAM) is addressed using a graphical method. The main contributions are a computational complexity that scales well with the size of the environment, the elimination of most of the linearization inaccuracies, and a more flexible and robust data association. We also present a detection criteria for closing loops. We show how multiple topological constraints can be imposed on the graphical solution by a process of coarse fitting followed by fine tuning. The coarse fitting is performed using an approximate system. This approximate system can be shown to possess all the local symmetries. Observations made during the SLAM process often contain symmetries, that is to say, directions of change to the state space that do not affect the observed quantities. It is important that these directions do not shift as we approximate the system by, for example, linearization. The approximate system is both linear and block diagonal. This makes it a very simple system to work with especially when imposing global topological constraints on the solution. These global constraints are nonlinear. We show how these constraints can be discovered automatically. We develop a method of testing multiple hypotheses for data matching using the graph. This method is derived from statistical theory and only requires simple counting of observations. The central insight is to examine the probability of not observing the same features on a return to a region. We present results with data from an outdoor scenario using a SICK laser scanner. View full abstract»

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  • Robust Recognition of Simultaneous Speech by a Mobile Robot

    Page(s): 742 - 752
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (445 KB) |  | HTML iconHTML  

    This paper describes a system that gives a mobile robot the ability to perform automatic speech recognition with simultaneous speakers. A microphone array is used along with a real-time implementation of geometric source separation (GSS) and a postfilter that gives a further reduction of interference from other sources. The postfllter is also used to estimate the reliability of spectral features and compute a missing feature mask. The mask is used in a missing feature theory-based speech recognition system to recognize the speech from simultaneous Japanese speakers in the context of a humanoid robot. Recognition rates are presented for three simultaneous speakers located at 2 m from the robot. The system was evaluated on a 200-word vocabulary at different azimuths between sources, ranging from 10deg to 90deg. Compared to the use of the microphone array source separation alone, we demonstrate an average reduction in relative recognition error rate of 24% with the postfllter and of 42% when the missing features approach is combined with the postfllter. We demonstrate the effectiveness of our multisource microphone array postfilter and the improvement it provides when used in conjunction with the missing features theory. View full abstract»

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  • Modelless Guidance for the Docking of Autonomous Vehicles

    Page(s): 753 - 762
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1136 KB) |  | HTML iconHTML  

    A novel line-of-sight sensing-based modelless guidance strategy is presented for the autonomous docking of robotic vehicles. The novelty of the proposed guidance strategy is twofold: 1) applicability to situations that do not allow for direct proximity measurement of the vehicle and 2) ability to generate short-range docking motion commands without a need for a global sensing-system (calibration) model. Two guidance -based motion-planning methods were developed to provide the vehicle controller with online corrective motion commands: a passive-sensing-based and an active-sensing-based scheme, respectively. The objective of both proposed guidance methods is to minimize the accumulated systematic errors of the vehicle as a result of the long-range travel, while allowing it to converge to its desired pose within random-noise limits. Both techniques were successfully tested via simulations and experiments, and are discussed herein, in terms of convergence rate and accuracy, in addition to the types of localization problems for which each method could be specifically more suitable. View full abstract»

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  • Whole-Body Motion Generation Integrating Operator's Intention and Robot's Autonomy in Controlling Humanoid Robots

    Page(s): 763 - 775
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3310 KB) |  | HTML iconHTML  

    This paper introduces a framework for whole-body motion generation integrating operator's control and robot's autonomous functions during online control of humanoid robots. Humanoid robots are biped machines that usually possess multiple degrees of freedom (DOF). The complexity of their structure and the difficulty in maintaining postural stability make the whole-body control of humanoid robots fundamentally different from fixed-base manipulators. Getting hints from human conscious and subconscious motion generations, the authors propose a method of generating whole-body motions that integrates the operator's command input and the robot's autonomous functions. Instead of giving commands to all the joints all the time, the operator selects only the necessary points of the humanoid robot's body for manipulation. This paper first explains the concept of the system and the framework for integrating operator's command and autonomous functions in whole-body motion generation. Using the framework, autonomous functions were constructed for maintaining postural stability constraint while satisfying the desired trajectory of operation points, including the feet, while interacting with the environment. Finally, this paper reports on the implementation of the proposed method to teleoperate two 30-DOF humanoid robots, HRP-1S and HRP-2, by using only two 3-DOF joysticks. Experiments teleoperating the two robots are reported to verify the effectiveness of the proposed method. View full abstract»

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  • Quantitative Comparison of Bilateral Teleoperation Systems Using μ-Synthesis

    Page(s): 776 - 789
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1092 KB) |  | HTML iconHTML  

    This paper presents a quantitative comparison framework for bilateral teleoperation systems (BTSs) that have different dynamic characteristics and sensory configurations for a given task-dependent performance objective (TDPO). mu-synthesis is used to develop the framework since it can efficiently treat systems containing uncertainties and disturbances. The framework consists of: 1) a feasibility test and 2) a comparison methodology using prioritized TDPOs. As the formulation used is based on mu-synthesis, the system, operator, and environment models are represented in the form of linear nominal models with frequency-dependent multiplicative uncertainties. This framework is applied to a BTS including an uncertain human operator and environment in a practical case study. The validity of the proposed quantitative framework is confirmed through experiments. The proposed framework can be used as a tool to design BTSs, especially when there are constraints in designing drive mechanisms and choosing sensory configurations. View full abstract»

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  • Rhythmic Feedback Control of a Blind Planar Juggler

    Page(s): 790 - 802
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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (568 KB) |  | HTML iconHTML  

    The paper considers the feedback stabilization of periodic orbits in a planar juggler. The juggler is "blind," i.e, he has no other sensing capabilities than the detection of impact times. The robustness analysis of the proposed control suggests that the arms acceleration at impact is a crucial design parameter even though it plays no role in the stability analysis. Analytical results and convergence proofs are provided for a simplified model of the juggler. The control law is then adapted to a more accurate model and validated in an experimental setup. View full abstract»

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  • Robust PD Control Using Adaptive Compensation for Completely Restrained Parallel-Wire Driven Robots: Translational Systems Using the Minimum Number of Wires Under Zero-Gravity Condition

    Page(s): 803 - 812
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (517 KB) |  | HTML iconHTML  

    A parallel-wire driven mechanism uses flexible wires instead of heavy rigid links. In this paper, we propose a robust point-to-point (PTP) position control method in the task-oriented coordinates for completely restrained parallel wire-driven robots, which are translational systems using the minimum number of wires under zero-gravity conditions. In the cases where parallel-wire driven robots are disassembled/assembled and used outdoors (also applied in space), actuator positions would be uncertain or contain some errors. The error of internal force among wires that results from such uncertainty of actuator positions deteriorates positioning performance. To overcome such a difficulty, adaptive compensation is employed for robust PD control against the error of internal force, in this paper. It is necessary for the adaptive compensation to separate the internal force term linearly into a regressor matrix and a parameter vector concerned with the errors of actuator positions. The internal force term, however, possesses the nonlinear characteristic concerned with the errors of actuator position. Noting the structure of the internal force term, this paper shows that measuring both the position of an end-effector and wire length in real time enables the linear separation. Not only does this robust PD control method ensure precise positioning using external sensors; it enhances the robustness for uncertainty of the Jacobian matrix, which results from the error of actuator installation. First, we explain the linearization of the internal force term. Next, the robust PD control for the parallel-wire driven system using the uncertain Jacobian matrix is proposed; then, we prove the motion convergence to desired points and discuss its robustness based on Lyapunov stability analysis. Finally, the usefulness of the proposed control method is demonstrated through experiments and simulations. View full abstract»

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  • Potential Fields for Maintaining Connectivity of Mobile Networks

    Page(s): 812 - 816
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (483 KB) |  | HTML iconHTML  

    The control of mobile networks of multiple agents raises fundamental and novel problems in controlling the structure of the resulting dynamic graphs. In this paper, we consider the problem of controlling a network of agents so that the resulting motion always preserves the connectivity property of the network. In particular, the connectivity condition is translated to differentiable constraints on individual agent motion by considering the dynamics of the Laplacian matrix and its spectral properties. Artificial potential fields are then used to drive the agents to configurations away from the undesired space of disconnected networks while avoiding collisions with each other. We conclude by illustrating a class of interesting problems that can be achieved while preserving connectivity constraints. View full abstract»

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  • Convex Optimization Algorithms for Active Balancing of Humanoid Robots

    Page(s): 817 - 822
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (505 KB) |  | HTML iconHTML  

    We show that a large class of active balancing problems for legged robots can be framed as a second-order cone programming (SOCP) problem, a convex optimization problem for which efficient and numerically robust algorithms exist. We describe this general SOCP balancing framework, show that several existing optimization-based balancing strategies reduce to special cases of this more general formulation, and investigate the computational performance of our SOCP algorithms through simulation studies involving a humanoid model. View full abstract»

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  • Gyrobot: Control of Multiple Degree of Freedom Underactuated Mechanisms Using a Gyrating Link and Cyclic Braking

    Page(s): 822 - 827
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (233 KB) |  | HTML iconHTML  

    A novel control strategy is introduced in which a multiple degree of freedom passive joint mechanism is augmented with a single continuously gyrating link. The gyrating link introduces coupling torques to the remaining joints, and the effect of these torques is controlled by cyclically applying holding brakes mounted on the passive joints. This allows position and trajectory control of the mechanism. View full abstract»

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  • Virtual-Holonomic-Constraints-Based Design of Stable Oscillations of Furuta Pendulum: Theory and Experiments

    Page(s): 827 - 832
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    The Furuta pendulum consists of an arm rotating in the horizontal plane and a pendulum attached to its end. Rotation of the arm is controlled by a DC motor, while the pendulum is moving freely in the plane, orthogonal to the arm. Motivated, in particular, by possible applications for walking/running/balancing robots, we consider the Furuta pendulum as a system for which synchronized periodic motions of all the generalized coordinates are to be created and stabilized. The goal is to achieve, via appropriate feedback control action, orbitally exponentially stable oscillations of the pendulum of various shapes around its upright and downward positions, accompanied with oscillations of the arm. Our approach is based on the idea of stabilization of a particular virtual holonomic constraint imposed on the configuration coordinates, which has been theoretically developed recently. Here, we elaborate on the complete design procedure. The results are illustrated not only through numerical simulations but also through successful experimental tests. View full abstract»

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  • Corrections to “Dynamic Modeling and Experimental Validation for Interactive Endodontic Simulation” [Jun 07 443-458]

    Page(s): 833
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    In the above titled paper (ibid., vol. 23, no. 3, pp. 443-458, Jun 07), Fig. 11 was printed with some mathematical symbols missing in lines 3, 6, 8, and 13. The corrected figure and its caption are presented here. View full abstract»

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  • ICRA 2008

    Page(s): 834
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  • Special issue on Visual SLAM

    Page(s): 835
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  • Explore IEL IEEE's most comprehensive resource [advertisement]

    Page(s): 836
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    Freely Available from IEEE
  • IEEE Robotics and Automation Society Information

    Page(s): C3
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Aims & Scope

IEEE Transactions on Robotics covers both theory and applications on topics including: kinematics, dynamics, control, and simulation of robots and intelligent machines and systems.

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Meet Our Editors

Editor-in-Chief
Frank Park
Seoul National University