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Advanced Robotics, 2009. ICAR 2009. International Conference on

Date 22-26 June 2009

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Displaying Results 1 - 25 of 154
  • RFID tag bearing estimation for mobile robot localization

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (773 KB) |  | HTML iconHTML  

    Passive RFID provides an inexpensive and effective support to basic mobile robot navigation tasks. Nonetheless, problems related to interference and reflections of the signal, and missing tag range and bearing information are open. In this paper, we present a novel method to estimate the bearing of a passive tag relative to a mobile robot equipped with RFID reader and antennas. The algorithm relies on fuzzy reasoning to both model the RFID device and estimate the tag bearing. As an application of the approach, we describe a landmark-based method to solve the so-called kidnapped robot problem, using tag bearing information and a single visual landmark. Experimental results are presented, proving the effectiveness of the proposed technique. It is shown that the combination of RFID and vision provides accurate robot pose information comparable to that of laser-based Monte Carlo localization, with the additional advantage of relying on low-cost sensors. View full abstract»

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  • Vision-based human augmented mapping for indoor environments

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1572 KB) |  | HTML iconHTML  

    In this paper, we suggest a new method of vision-based human augmented mapping for indoor environments. It is a semi-autonomous approach using human-robot interation and can be an alternative to autonomous map building. The advantage of our approach is that the user can share the environments with the robot and insert semantic information to the environmental map. We apply PCA features for visual landmarks and employ hybrid map representation. Particularly, we define two types of nodes, U/R-nodes and divide the map building process into two, user's guidance and robot's review. Experimental results in rectangular-shaped corridors show the feasibility of our method. View full abstract»

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  • Modelling and control of the GreenWeeder for crop row tracking

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (860 KB) |  | HTML iconHTML  

    GreenWeeder is a non-herbicidal autonomous weeding robot that is being developed to autonomously track crop rows to target inter-row spacing for weeding through electrocution. This work presents the experimental system identification to identify the steering system dynamics and the development of a controller to track an especially laid strip mimicking a crop row. The results of the designed controller are presented and analyzed in order to improve the performance as well as the accuracy of the robot lateral deviation from the crop rows. View full abstract»

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  • On the use of iterative LCP solvers for dry frictional contacts in grasping

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (720 KB) |  | HTML iconHTML  

    In this paper we propose the use of new iterative methods to solve symmetric linear complementarity problems (SLCP) that arise in the computation of dry frictional contacts in multi-rigid-body dynamics. Specifically, we explore the two-stage iterative algorithm developed by Morales, Nocedal and Smelyanskiy. The underlying idea of that method is to combine projected Gauss-Seidel iterations with subspace minimization steps. Gauss-Seidel iterations are aimed to obtain a high quality estimation of the active set. Subspace minimization steps focus on the accurate computation of the inactive components of the solution. Overall the new method is able to compute fast and accurate solutions of severely ill-conditioned LCPs. We compare the performance of a modification of the iterative method of Morales et al with Lemke's algorithm on robotic object grasping problems. View full abstract»

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  • Measurement of static constraints imposed by a human hand on a grasped object

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (823 KB) |  | HTML iconHTML  

    This paper proposes a method of directly measuring static constraints imposed by a human hand on a grasped object. Based on the analysis of the demonstration data of the human grasp, the static constraints are expressed as a combination of frictional force and normal force generated by the human hand. The static constraints are an important property to be mapped to robotic hands in the programming-by-demonstration. Measured static constraints are to be generated to robotic hands to establish the stable grasp. In the experiments, we have successfully measured the static constraints appeared in various different grasps used in the daily human life. View full abstract»

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  • Moving obstacles detection and tracking with laser range finder

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (308 KB) |  | HTML iconHTML  

    This paper deals with a problem which is basic to mobile robot navigation in dynamic environments: the perception of dynamic objects. This required as a first step the extraction of mobile objects present in the environment tacking into account the effect of the embedded sensor motion. In the proposed algorithm, the laser data are used in the development of a clustering-based approach. The second step deals with dynamic objects tracking. This is achieved by a set of Extended Kalman Filters (EKF) where an EKF is initialized for each mobile object and evaluated for the prediction and update phases. The results of several experiments are illustrated, confirming the effectiveness of the proposed system. View full abstract»

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  • Maximum likelihood point cloud acquisition from a mobile platform

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (3396 KB) |  | HTML iconHTML  

    This paper describes an approach to acquire locally consistent range data scans from a moving sensor platform. Data from a vertically mounted rotating laser scanner and odometry position estimates are fused and used to estimate maximum likelihood point clouds. An estimation algorithm is applied to reduce the accumulated error after a full rotation of the range finder. A configuration consisting of a SICK laser scanner mounted on a rotational actuator is described and used to evaluate the proposed approach. The data sets analyzed suggest a significant improvement in point cloud consistency, even over a short travel distance. View full abstract»

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  • Model predictive collaborative motion planning and control of mobile robots including safety aspects

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (259 KB) |  | HTML iconHTML  

    One main problem in multi-robot systems is the coordinated navigation of the autonomous robots. Hereby, the robots have to fulfill their respective tasks while avoiding collisions with other moving robots. In addition, problem-specific differential constraints like limitations of the velocities and accelerations have to be considered. Coordinated navigation of such a multi-robot system therefore has to combine contradicting aspects like efficient task accomplishment and the fulfillment of safety and problem-specific constraints in parallel. This work focuses on a two-level model predictive optimizing approach. On a global long-term level, simple dynamic models of the robots are used to compute optimal paths under differential constraints where a safety distance between all robots is achieved. Since many uncertainties and unforeseen events could occur, all robots are additionally using a nonlinear model predictive control approach on a local real-time level. This control approach solves the path following and the collision avoidance problem in parallel while also considering differential constraints of the single robots. View full abstract»

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  • Multi-modal force/vision sensor fusion in 6-DOF pose tracking

    Page(s): 1 - 8
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (886 KB) |  | HTML iconHTML  

    Sensor based robot control allows manipulation in dynamic and uncertain environments. Vision can be used to estimate 6-DOF pose of an object by model-based pose-estimation methods, but the estimate is not accurate in all degrees of freedom. Force offers a complementary sensor modality allowing accurate measurements of local object shape when the tooltip is in contact with the object. As force and vision are fundamentally different sensor modalities, they cannot be fused directly.We present a method which fuses force and visual measurements using positional information of the end-effector. By transforming the position of the tooltip and the camera to a same coordinate frame and modeling the uncertainties of the visual measurement, the sensors can be fused together in an Extended Kalman filter. Experimental results show greatly improved pose estimates when the sensor fusion is used. View full abstract»

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  • Robust control of robots with variable joint stiffness

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (266 KB) |  | HTML iconHTML  

    The development of safe and dependable robots for physical human-robot interaction requires both the mechanical design of lightweight and compliant manipulators and the definition of motion control laws that allow compliant behavior in reaction to possible collisions, while preserving accuracy and performance during the motion in the free space. For these motivations, great attention has been posed in the design of robots manipulators with relevant and programmable joint/transmission stiffness. A robust control strategy for a general class of multi-dof manipulators with variable joint stiffness is presented in this paper. The proposed control scheme is based on three elements: the first one compensates for the robot dynamics, the second one is based on a linear controller to impose a desired behavior, while a smooth sliding mode control action is added to ensure robustness with respect to model uncertainties. The stability of the overall system is studied by using the direct Lyapunov method. The effectiveness of the proposed approach is demonstrated by simulation analysis. View full abstract»

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  • LQ control design of cooperative teleoperation systems

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (965 KB) |  | HTML iconHTML  

    In this paper, two control architectures for cooperative teleoperation systems based on wave variables and optimal control are presented and discussed. The cooperative control schemes consider two pairs of wave based teleoperation systems collaborating to carry out operations in a shared remote environment. The information exchange occurs only between the corresponding pair, and the slave robots may physically interact between themselves either through a common tool or the manipulated object. Simulation results show the good performance of the proposed framework. View full abstract»

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  • A versatile Generalized Inverted Kinematics implementation for collaborative working humanoid robots: The Stack Of Tasks

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (289 KB) |  | HTML iconHTML  

    This paper present a framework called the stack of tasks (SoT) implementing a generalized inverted kinematics. This particular implementation provides a run-time graph of computational nodes. It can be modified through a specifically targeted scripting language. It allows hybrid control scheme necessary for complex robot applications such as a HRP-2 humanoid robot in a collaborative working environment. We also show through a case study that this framework allows an efficient integration in nowadays middleware such as CORBA. View full abstract»

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  • On path errors of redundant robots in fault tolerant operations for locked joint failures

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (238 KB) |  | HTML iconHTML  

    While a redundant robot is still able to continue the desired task in the presence of locked joint failures, its end-effector error both at the instant of locking joint and in post-failure operations will increase obviously. This work discusses the path error of a redundant robot in fault tolerant operations for locked-joint failures. First, the analytical formula of the optimal joint velocity with minimum jump is derived, and a new fault tolerant algorithm with the minimum jump is proposed. Then, the jump difference between the minimum jump solution and the least-norm velocity solution is mathematically analyzed. Finally numerical simulations and experimental studies are implemented with a planar 3R robot for the two algorithms. Study results indicate that the increase of the path error at the instant of locking joint mainly depends on the joint velocity jump; the increase of the path error in post-failure operations mainly depends on the joint velocity of the reduced robot. The new algorithm proposed in this paper can be used to reduce the path error at the instant of locking joint. View full abstract»

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  • Humanoid teleoperation system for space environments

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (561 KB) |  | HTML iconHTML  

    Our goal is to study collaborative working environments in which human and robotic agents can work together in the achievement of different tasks. The introduction of robots in the field of space applications becomes really useful when performing tasks that are too dangerous, too difficult or even impossible for humans. In this paper we present a teleoperation system for interacting with a humanoid robot in a space environment. A ldquolunar scenariordquo was built in which the HOAP-3 humanoid robot is able to detect and manipulate objects, with the help of a human operator. A human machine interface (HMI) and a high level command protocol have been developed for the teleoperation of the robot. The HMI allows an operator to control the robot movements and visualize the environment from robot cameras. View full abstract»

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  • Extraction of grasp-related features by human dual-hand object exploration

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (219 KB) |  | HTML iconHTML  

    We consider the problem of objects exploration for grasping purposes, specifically in cases where vision based methods are not applicable. A novel dual-hand object exploration method is proposed that takes benefits from a human demonstration to enrich knowledge about an object. The user handles an object freely using both hands, without restricting the object pose. A set of grasp-related features obtained during exploration is demonstrated and utilized to generate grasp oriented bounding boxes that are basis for pre-grasp hypothesis. We believe that such exploration done in a natural and user friendly way creates important link between an operator intention and a robot action. View full abstract»

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  • DESIRE WEB 2.0 - Integration management and distributed software development for service robots

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (298 KB) |  | HTML iconHTML  

    In the last decades many robotic demonstrators were built, the vast majority of which are constrained to a limited set of operations, often focusing on the development of single robotic components like navigation, manipulation, human-machine interaction, etc. These specialized robots thus are not intended and commonly also not flexible enough to solve many complex tasks, in particular concerning dynamic and unstructured environments, requiring the combination of different components. More recently there have been efforts to create robots that are capable of performing various tasks in households or public domain and are dependable enough for every-day use (e.g. DESIRE). This requires the integration of many expert technologies from the different robotic domains and different developers that are located at different places. A capable integration management is needed, including not only software engineering tools but support for distributed development and remote testing on robot hardware in particular. This paper proposes software engineering methods and tools that support integration and a new Web portal for the distributed development and remote testing of service robots. The Web portal permits centrally managed configuration, control and monitoring of software component processes through a user interface, that is available at any time from any place, through arbitrary operating systems. It is shown in the results, that the effort for organisation and coordination of hardware tests could be substantially reduced in the DESIRE project by the usage of the Web portal. View full abstract»

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  • Predicting the compliance of soft fingertips with differentiated layer design: A numerical and experimental investigation

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (597 KB) |  | HTML iconHTML  

    This paper describes the nonlinear finite elements analysis (FEA) of soft fingertips for robotic hands in contact conditions. The purpose is to test the reliability of FEA when designing fingertips with differentiated layer design, that is the adoption of a single elastic material, dividing the overall thickness of the pad into layers with different structural design (e.g. a continuous skin layer coupled with an internal layer with voids). The pads are shaped around a rigid core and their behavior is investigated under compressive contact loads. The applicability of various nonlinear hyperelastic constitutive models for predicting the pad behavior is explored under the hypothesis of large deflections. Two materials have been tested whose mechanical properties are determined experimentally. One of these materials can be used in rapid prototyping printers and its properties are presented for the first time. Experimental activity fully validates the proposed FEA models concerning homogeneous pads. At last two different and innovative pad geometries are proposed showing that FEA confirms to be a powerful tool for predicting the compliance of soft fingertips if the right hypothesis and simplifying assumptions are made. View full abstract»

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  • A parametric study on the passive dynamics of straight-ahead level-ground quadrupedal running

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (499 KB) |  | HTML iconHTML  

    This paper examines the passive dynamics of straight-ahead level ground quadrupedal running and explores its use in formulating design guidelines that would: a) reduce steady-state roll and b) self-stabilize the rolling motion, thus making the control of the robot more straightforward. To study the effect of mechanical design in the rolling motion, a simple bounding-in-place (BIP) template is introduced as a candidate frontal plane model that captures the targeted steady-state behavior of a straight-ahead level ground running quadruped robot. This model is parametrically analyzed and local stability analysis shows that the dynamics of the open loop passive system alone can confer stability of the motion! These results might explain the success of simple, open loop running controllers on existing experimental robots and can be further used in developing control methodologies for legged robots that take advantage of the mechanical system. View full abstract»

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  • Clustering of motion data from on-body wireless sensor networks for human-imitative walking in bipedal robots

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (936 KB) |  | HTML iconHTML  

    This paper presents an alternative inexpensive and rapid approach for programming behaviour in commercial off-the-shelf bipedal robots. It combines on-body wireless sensor networks to capture human motion and unsupervised learning algorithms to identify key features in human motion. This paper compares three unsupervised learning algorithms for the classification of motion data from an on-body orient motion capture system for training the KHR-1 bipedal robot. The results of the clustering were first compared in the Webots simulator and promising candidates were transferred to the real robot and the results of the experiments have been presented. The EM clustering algorithm worked best and the reason for this have been analysed. View full abstract»

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  • Lateral movement of flexible mono-tread mobile track (FMT) - Modeling, simulation and experiment -

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1018 KB) |  | HTML iconHTML  

    In the past decade, search robots in rescue operations have been focused on and developed for the purpose of finding survivors trapped in the rubble of collapsed buildings. However, serpentine mechanism which is a popular mobile system might gather to catch debris between tracks or become stuck due to the mechanisms, in addition, increasing the number of segments would result in gaining weight and complicated control system. We have, hence, proposed a new mobile mechanism: flexible mono-tread mobile track (FMT), and developed a prototype ldquoRescue mobile track No.2 (RT-02) WORMYrdquo. In the paper, a dynamic model for the FMT is derived in a sagittal and lateral plane to treat the movements. Then, some simulation are shown to analyze the lateral movement with respect to various pressure distribution affected by the retro-flexion. Finally, the analysis is validated through some experiments. View full abstract»

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  • Improving user interfaces of interactive robots with multimodality

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (534 KB) |  | HTML iconHTML  

    Interacting with robots like service robots should be as natural as possible for humans. As a consequence, such robots should be equipped with a multimodal user interface, so that interaction can rely on the relevant modalities for a given task and a given context. Typically, a rather fixed combination of speech and graphical user interface is used both for input and output. To enable more flexibility in the design of the interfaces and in the choice of modalities, we propose using an existing platform for model-driven generation of human-computer interfaces. In this paper, we present how the concepts of the platform apply to multimodal human-robot interaction as well, and we present an extension of the platform in this direction. To validate our approach, we investigated a simple user interface enabling the command of a mobile robot using dynamic gesture and speech. We provide some quantitative results of the performance of the fusion, which highlight not only the feasibility of the concept but also an interesting complementary of gesture and speech on the chosen task. View full abstract»

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  • Realization of a highly accurate mobile robot system for multi purpose precision forestry applications

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1014 KB) |  | HTML iconHTML  

    Localization, navigation and identification of characteristics of the environment are of high importance in mobile robotics. In this paper we used methods of mobile robotics to derive highly accurate position information of a wood harvester's cabin as well as of its harvesting head. In addition to enhance the harvesting process, the fusion of data provided by the sensors leads to a number of new applications in forestry ranging from high precision localization and logging operations up to single tree navigation. The first part of this paper introduces the components of this special form of a mobile robot. In the second part the underlying robotic principles are clarified and examples are given of how these principles enabled new applications in forestry. The results are evaluated and compared to conventional measurement techniques. View full abstract»

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  • Dexterous mobility with the uBot-5 mobile manipulator

    Page(s): 1 - 7
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (11813 KB) |  | HTML iconHTML  

    We present an initial demonstration of dexterous mobility using the uBot-5, a dynamically balancing mobile manipulator. Dexterous mobility refers generally to a level of bodily resourcefulness that permits the autonomous reassignment of effectors for the purpose of maintaining mobility in a variety of situations. We begin by describing a set of postural stability controllers in terms of a small number of simple control objectives. We then show how the resulting postures support dexterous mobility by enabling a new ldquoknuckle walkingrdquo mobility mode. In a preliminary experiment, we develop this mobility mode by formulating a practical reinforcement learning problem that allows the robot to learn an efficient gait on-line in a single trial. View full abstract»

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  • Miniature quad-rotor dynamics modeling & guidance for vision-based target tracking control tasks

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (4920 KB) |  | HTML iconHTML  

    This paper presents the dynamics modeling and the control & guidance architecture for specific target tracking indoors tasks using a miniature quad-rotor. Our objective is to develop a testbed using Matlab for experimentation and simulation of dynamics, control and guidance methods within a strong interplay between the hardware on board and software provisioned. View full abstract»

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  • FRC: A low-cost service robot for subsea flexible risers

    Page(s): 1 - 6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1316 KB) |  | HTML iconHTML  

    This paper presents the design and development of a semi-autonomous low-cost underwater service robot for subsea flexible risers, used for supplying oil from the deep sea to the offshore platforms and floating production, storage and offloading vessels (FPSO). The robot is designed in a modular way allowing flexibility and variety in use. It can provide various types of services according to user needs, such as carrying equipment for inspection and deploying tooling for repair. The robot moves along the riser like an inchworm does, thanks to a simple, yet versatile crawling mechanism. In addition, the robot can rotate around the riser indefinitely by using a similar principle. Novel under-actuated end-effectors have been conceived and developed to firmly hold the robot on the riser during locomotion, rotation or operation, without affecting riser integrity. In principle, the current design could operate up to 2000m sea depth with minor modifications. In this study, the service robot carries and deploys digital radiographic equipment for the volumetric inspection of flexible risers. Several preliminary tests, as well as a series of underwater tests proved the robot's encouragingly positive performance. View full abstract»

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