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  • Path planning for grasping operations using an adaptive PCA-based sampling method

     Rosell Gratacos, Joan; Suarez Feijoo, Raul; Perez Ruiz, Alexander
    Autonomous robots
    Date of publication: 2013-07-01
    Journal article

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    The planning of collision-free paths for a handarm robotic system is a difficult issue due to the large number of degrees of freedom involved and the cluttered environment usually encountered near grasping configurations. To cope with this problem, this paper presents a novel importance sampling method based on the use of principal component analysis (PCA) to enlarge the probability of finding collisionfree samples in these difficult regions of the configuration space with low clearance. By using collision-free samples near the goal, PCA is periodically applied in order to obtain a sampling volume near the goal that better covers the free space, improving the efficiency of sampling-based path planning methods. The approach has been tested with success on a hand-arm robotic system composed of a four-finger anthropomorphic mechanical hand (17 joints with 13 independent degrees of freedom) and an industrial robot (6 independent degrees of freedom).

  • Safe teleoperation of a dual hand-arm robotic system

     Rosell Gratacos, Joan; Suarez Feijoo, Raul; Pérez Ruiz, Alexander
    Iberian Robotics Conference
    Presentation's date: 2013-11-28
    Presentation of work at congresses

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  • Using path planning techniques to improve airway tree segmentation from CT images

     Cabras, Paolo; Rosell Gratacos, Joan
    International Conference on Bio-inspired Systems and signal Processing
    Presentation's date: 2013-02-13
    Presentation of work at congresses

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    Virtual Bronchoscopy (VB) permits the preplanning of operations concerning the airways and provides the necessary guidance to reach the pulmonary lesions. Fundamental for a good VB is the reconstruction of a 3D model of the airways from the CT images. Airway segmentation algorithms usually return the biggest detected volume connected to the trachea (the root tree), but many of them also reconstruct during the segmentation process, small parts not connected to the root tree. To overcome this problem this paper proposes a method, based on path planning techniques, that is able to connect the small isolated pieces of bronchi to the terminal points of the root airway tree, taking into account the growing direction of the branches and the gray values of the CT images. As a result, a more complete 3D model of the airways is obtained.

  • Haptic aids for bilateral teleoperators

     Pérez Ruiz, Alexander; Rosell Gratacos, Joan
    Iberian Robotics Conference
    Presentation's date: 2013-11-28
    Presentation of work at congresses

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    Teleoperation of robotic tasks is usually performed in the Cartesian space due to the kinematic differences between the master and the slave. This entails several requirements, like the definition of a proper mapping between workspaces, the need to avoid collisions of the teleoperated robot with the environment, and the use of the inverse kinematics and of a procedure to correctly manage the passing through singularities. Within a bilateral teleoperation framework to teleoperate an industrial robot with a desktop haptic device, the present work proposes a guiding system based on path planning techniques to cope with these issues. The proposed system also includes a reactive behavior to cope with the potential collisions with obstacles. Teleoperation tests on virtual and real scenarios are included to validate the approach.

  • Hybrid mapping for the assistance of teleoperated grasping tasks

     Colasanto, Luca; Suarez Feijoo, Raul; Rosell Gratacos, Joan
    IEEE transactions on systems man and cybernetics Part A-systems and humans
    Date of publication: 2013-09-12
    Journal article

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    Teleoperating a robotic hand with the aid of a sensorized glove presents some particular problems. A certain problem is due to the kinematic differences between the human hand and the robotic hand, which do not allow a simple direct mapping of the sensor readings from the glove to the robotic hand. This problem is addressed with different types of mapping, but none of them is of general use. This paper proposes two new mappings within two existing mapping types, as well as a new hybrid mapping that combines the best features of these existing mapping types. This hybrid mapping allows intuitive free space movements (where the gesture is more important than the precise positions of the fingers) and grasp movements (where the precise positions of the fingers is more important than the gesture), despite kinematic differences between the human hand and the robotic hand. The approach has been implemented, and some illustrative examples are presented in this paper.

  • A three-stage method for the 3D reconstruction of the tracheobronchial tree from CT scans

     Rosell Gratacos, Joan; Cabras, Paolo
    Computerized medical imaging and graphics
    Date of publication: 2013-10
    Journal article

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    This paper proposes a method for segmenting the airways from CT scans of the chest to obtain a 3D model that can be used in the virtual bronchoscopy for the exploration and the planning of paths to the lesions. The method is composed of 3 stages: a gross segmentation that reconstructs the main airway tree using adaptive region growing, a finer segmentation that identifies any potential airway region based on a 2D process that enhances bronchi walls using local information, and a final process to connect any isolated bronchus to the main airways using a morphologic reconstruction process and a path planning technique. The paper includes two examples for the evaluation and discussion of the proposal. © 2013 Elsevier Ltd.

  • Numerical Computation and Avoidance of Manipulator Singularities  Open access

     Bohigas Nadal, Oriol
    Defense's date: 2013-05-10
    Universitat Politècnica de Catalunya
    Theses

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    This thesis develops general solutions to two open problems of robot kinematics: the exhaustive computation of the singularity set of a manipulator, and the synthesis of singularity-free paths between given configurations. Obtaining proper solutions to these problems is crucial, because singularities generally pose problems to the normal operation of a robot and, thus, they should be taken into account before the actual construction of a prototype. The ability to compute the whole singularity set also provides rich information on the global motion capabilities of a manipulator. The projections onto the task and joint spaces delimit the working regions in such spaces, may inform on the various assembly modes of the manipulator, and highlight areas where control or dexterity losses can arise, among other anomalous behaviour. These projections also supply a fair view of the feasible movements of the system, but do not reveal all possible singularity-free motions. Automatic motion planners allowing to circumvent problematic singularities should thus be devised to assist the design and programming stages of a manipulator. The key role played by singular configurations has been thoroughly known for several years, but existing methods for singularity computation or avoidance still concentrate on specific classes of manipulators. The absence of methods able to tackle these problems on a sufficiently large class of manipulators is problematic because it hinders the analysis of more complex manipulators or the development of new robot topologies. A main reason for this absence has been the lack of computational tools suitable to the underlying mathematics that such problems conceal. However, recent advances in the field of numerical methods for polynomial system solving now permit to confront these issues with a very general intention in mind. The purpose of this thesis is to take advantage of this progress and to propose general robust methods for the computation and avoidance of singularities on non-redundant manipulators of arbitrary architecture. Overall, the work seeks to contribute to the general understanding on how the motions of complex multibody systems can be predicted, planned, or controlled in an efficient and reliable way.

    Aquesta tesi desenvolupa solucions generals per dos problemes oberts de la cinemàtica de robots: el càlcul exhaustiu del conjunt singular d'un manipulador, i la síntesi de camins lliures de singularitats entre configuracions donades. Obtenir solucions adequades per aquests problemes és crucial, ja que les singularitats plantegen problemes al funcionament normal del robot i, per tant, haurien de ser completament identificades abans de la construcció d'un prototipus. La habilitat de computar tot el conjunt singular també proporciona informació rica sobre les capacitats globals de moviment d'un manipulador. Les projeccions cap a l'espai de tasques o d'articulacions delimiten les regions de treball en aquests espais, poden informar sobre les diferents maneres de muntar el manipulador, i remarquen les àrees on poden sorgir pèrdues de control o destresa, entre d'altres comportaments anòmals. Aquestes projeccions també proporcionen una imatge fidel dels moviments factibles del sistema, però no revelen tots els possibles moviments lliures de singularitats. Planificadors de moviment automàtics que permetin evitar les singularitats problemàtiques haurien de ser ideats per tal d'assistir les etapes de disseny i programació d'un manipulador. El paper clau que juguen les configuracions singulars ha estat àmpliament conegut durant anys, però els mètodes existents pel càlcul o evitació de singularitats encara es concentren en classes específiques de manipuladors. L'absència de mètodes capaços de tractar aquests problemes en una classe suficientment gran de manipuladors és problemàtica, ja que dificulta l'anàlisi de manipuladors més complexes o el desenvolupament de noves topologies de robots. Una raó principal d'aquesta absència ha estat la manca d'eines computacionals adequades a les matemàtiques subjacents que aquests problemes amaguen. No obstant, avenços recents en el camp de mètodes numèrics per la solució de sistemes polinòmics permeten ara enfrontar-se a aquests temes amb una intenció molt general en ment. El propòsit d'aquesta tesi és aprofitar aquest progrés i proposar mètodes robustos i generals pel càlcul i evitació de singularitats per manipuladors no redundants d'arquitectura arbitrària. En global, el treball busca contribuir a la comprensió general sobre com els moviments de sistemes multicos complexos es poden predir, planificar o controlar d'una manera eficient i segura

  • Estimación de la forma de un objeto deformable mediante integración de visión y tacto

     Del Castillo pérez, Esteban
    Defense's date: 2013-09-30
    Universitat Politècnica de Catalunya
    Theses

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  • Haptic guidance using primitives for the execution of virtual robotic tasks

     Vázquez Hurtado, Carlos; Rosell Gratacos, Joan
    IEEE Electronics, Robotics and Automotive Mechanics Conference
    Presentation's date: 2012-11-20
    Presentation of work at congresses

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    Haptic guidance is a powerful tool for people rehabilitation, for handcraft skills acquisition and all kind of enactive tasks. In this paper, different techniques to achieve reliable haptic feedback on the execution of virtual robotic tasks, based on the efficient combination of path planning methods and haptic guidance primitives, are presented. Abstract The main contribution of this paper is a reliable system of force guidance based on haptic primitives. The whole proposal is constituted by: 1) a free collision path obtained using a deterministic sampling, hierarchical cell decomposition and harmonic functions 2) force feedback, achieved by means of elastic models, based on simple geometry elements, called haptic primitives, and 3) a virtual robotic task.

    Haptic guidance is a powerful tool for people rehabilitation, for handcraft skills acquisition and all kind of enactive tasks. In this paper, different techniques to achieve reliable haptic feedback on the execution of virtual robotic tasks, based on the efficient combination of path planning methods and haptic guidance primitives, are presented. The main contribution of this paper is a reliable system of force guidance based on haptic primitives. The whole proposal is constituted by: 1) a free collision path obtained using a deterministic sampling, hierarchical cell decomposition and harmonic functions 2) force feedback, achieved by means of elastic models, based on simple geometry elements,called haptic primitives, and 3) a virtual robotic task.

  • Motion planning for the virtual bronchoscopy

     Rosell Gratacos, Joan; Perez Ruiz, Alexander; Cabras, Paolo; Rosell, Antoni
    IEEE International Conference on Robotics and Automation
    Presentation's date: 2012-05-16
    Presentation of work at congresses

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    Bronchoscopy is an interventional medical procedure employed to analyze the interior side of the human airways, clear possible obstructions and biopsy. Using a 3D reconstruction of the tracheobronchial tree, Virtual Bronchoscopy (VB) may help physicians in the exploration of peripheral lung lesions. We are developing a haptic-based navigation system for the VB that allows the navigation within the airways using a haptic device whose permitted motions mimics those done with the real bronchoscope. This paper describes the motion planning module of the system devoted to plan a path from the trachea to small peripheral pulmonary lesions, that takes into account the geometry and the kinematic constraints of the bronchoscope. The motion planner output is used to visually and haptically guide the navigation during the virtual exploration using the haptic device. Moreover, physicians can get useful information of whether the peripheral lesions can effectively be reached with a given bronchoscope or of which is the nearest point to the lesion that can be reached.

  • Asistencia háptica basada en planificación de movimientos para la teleoperación cooperativa de sistemas multirobot  Open access

     Perez Ruiz, Alexander
    Defense's date: 2012-10-17
    Institute of Industrial and Control Engineering (IOC), Universitat Politècnica de Catalunya
    Theses

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    This work proposes a framework for the teleoperation of anthropomorphic industrial robots using desktop haptic devices that provides an aid to the operator in the form of haptic guidance based on path planning techniques. The teleoperation framework incorporates a new model of correspondence mapping between the workspace of the haptic device used to command the remote node and that of the robot. The mapping takes into account the position and orientation of the active camera that provides the video fed back from the remote node. The main features of this system are: 1. The user can change the position of the active camera to increase the visibility or to change the scales related to the workspaces in order to set the precision. 2. The user feels slight guiding forces that attract and push him/her to the path towards the goal configuration, particularly when it contains configuration changes. 3. When the operator requests it or when he/she reaches the limits of the workspace of the haptic device, the assistance system calculates the new configuration for the haptic device, taking over the teleoperation and guiding the operator to that configuration where teleoperation can resume. All kinesthetic aids are generated based on a Planner which includes a novel algorithm that is able to find feasible paths between both static and mobile obtacles or a mitxture of both. The main features of the proposed Planner are: 1. It is based on a Probabilistic RoadMap strategy based on a lazy evaluation of the possible collisions of the path. 2. It uses a reduced graph to find the solution path, which is a subset of a larger graph, thus ensuring both computational efficiency and coverage of the whole configuration space. 3. Each planned path is evaluated and iteratively improved by creating a new set of samples closer to the obstacles when any edge-validation fails. 4. Replanning is useful when moving obstacles are present or when the initial configuration changes and this process always brings as a result a new path very close to the one previously valid. The Planner frees the user from paying attention to potential collisions between the environment and any part of the robot (not only the end-effector, as other approaches do). This can be applied especially in multi-robot environments, where the other robots present in the cell may interfere with the remote teleoperated movements. The planner deals with other robots as collections of moving obstacles. The bilateral control scheme of the teleoperation system ensures its stability despite time delays. Additionally, the system influences on the remote node damping factor as a way of dealing with potential collisions, slowing the teleoperation when the system detects one. The system has been validated with multiple users, both in simulated environments and with the real robot, and it has shown that with the use of its assistance the operator increases speed and security in performance, lightening the burden of teleoperation, especially when there are moving obstacles.

    En el presente trabajo se propone un marco para la teleoperación de robots industriales antropomórficos que cuenta con elementos de ayuda al operador en forma de guiado háptico basado en técnicas de planificación de caminos (path planning) para facilitarle su labor. Incorpora un novedoso modelo de correspondencia entre el espacio de trabajo del dispositivo háptico con el que va a ser comandado y el del robot. Esta correspondencia tiene en cuenta la posición y orientación de la cámara activa que proporciona el video desde el sitio remoto. Las principales características de este sistema son: 1. El usuario puede cambiar de cámara activa para incrementar la visibilidad o cambiar las escalas que relacionan los espacios de trabajo para ajustar la precisión. 2. El usuario experimenta ligeras fuerzas de guiado que lo atraen hacia el camino planificado y también lo empujan a lo largo del mismo hacia la configuración objetivo, en particular cuando contiene cambios de configuración. 3. Cuando se alcanzan los limites del espacio de trabajo del dispositivo háptico o cuando el usuario lo solicita, se calcula la nueva configuración de este dispositivo, desde donde pueda retomar y efectuar la teleoperación y lo guía hasta ella. Las ayudas hápticas son generadas a partir de un camino que soluciona la tarea. Para lo cual se ha desarrollado un planificador que incorpora un novedoso algoritmo que es capaz de encontrar caminos realizables tanto entre obstáculos estáticos como entre móviles o la mezcla de unos y otros. Las principales características del planificador propuesto en el presente trabajo son: 1. Está basado en un planificador de mapa de carreteras probabilístico (Probabilistic Roadmap) con evaluación tardía de las colisiones del camino encontrado. 2. Se reduce la cantidad de muestras que componen el grafo donde se busca la solución a partir de uno más grande que cubre el espacio de configuraciones. 3. Cada camino planificado es evaluado y mejorado progresivamente de forma iterativa, creando un nuevo conjunto de muestras cerca de los obstáculos cuando la validación de alguna arista falla. 4. Es útil para replanificar cuando están presentes obstáculos móviles o cuando la configuración inicial cambia, dando siempre como resultado un camino muy cercano al anteriormente válido. Con esta ayuda el usuario se libera de prestar atención a las potenciales colisiones de cualquier parte del robot con el entorno y no solamente del efector final del robot (TCP) como se hace en otros enfoques. Esto es aplicado especialmente en entornos multirobot donde los otros robots presentes en la celda remota pueden interferir con los movimientos teleoperados y que en este trabajo son considerados como colecciones de obstáculos móviles. El esquema de control del sistema de teleoperación bilateral, garantiza la estabilidad a pesar de los retardos de las variables. Adicionalmente, se influye sobre su factor de amortiguamiento en el nodo remoto como una forma de hacer frente a potenciales colisiones, ralentizando la teleoperación cuando se advierte una potencial colisión. El sistema ha sido validado con varios usuarios, tanto en simulación como en experimentación con el robot real,mostrando que con esta asistencia se incrementa la velocidad y la seguridad en la ejecución de la tarea y se aligera la carga de la teleoperación, en especial cuando existen obstáculos móviles.

  • Distance-Based Formulations For The Position Analysis Of Kinematic Chains  Open access

     Rojas Libreros, Nicolás Enrique
    Defense's date: 2012-06-20
    Institute of Industrial and Control Engineering (IOC), Universitat Politècnica de Catalunya
    Theses

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    This thesis addresses the kinematic analysis of mechanisms, in particular, the position analysis of kinematic chains, or linkages, that is, mechanisms with rigid bodies (links) interconnected by kinematic pairs (joints). This problem, of completely geometrical nature, consists in finding the feasible assembly modes that a kinematic chain can adopt. An assembly mode is a possible relative transformation between the links of a kinematic chain. When an assignment of positions and orientations is made for all links with respect to a given reference frame, an assembly mode is called a configuration. The methods reported in the literature for solving the position analysis of kinematic chains can be classified as graphical, analytical, or numerical. The graphical approaches are mostly geometrical and designed to solve particular problems. The analytical and numerical methods deal, in general, with kinematic chains of any topology and translate the original geometric problem into a system of kinematic analysis of all the Assur kinematic chains resulting from replacing some of its revolute joints by slider joints. Thus, it is concluded that the polynomials of all fully-parallel planar robots can be derived directly from that of the widely known 3-RPR robot. In addition to these results, this thesis also presents an efficient procedure, based on distance and oriented area constraints, and geometrical arguments, to trace coupler curves of pin-jointed Gr¨ubler kinematic chains. All these techniques and results together are contributions to theoretical kinematics of mechanisms, robot kinematics, and distance plane geometry. equations that defines the location of each link based, mainly, on independent loop equations. In the analytical approaches, the system of kinematic equations is reduced to a polynomial, known as the characteristic polynomial of the linkage, using different elimination methods —e.g., Gr¨obner bases or resultant techniques. In the numerical approaches, the system of kinematic equations is solved using, for instance, polynomial continuation or interval-based procedures. In any case, the use of independent loop equations to solve the position analysis of kinematic chains, almost a standard in kinematics of mechanisms, has seldom been questioned despite the resulting system of kinematic equations becomes quite involved even for simple linkages. Moreover, stating the position analysis of kinematic chains directly in terms of poses, with or without using independent loop equations, introduces two major disadvantages: arbitrary reference frames has to be included, and all formulas involve translations and rotations simultaneously. This thesis departs from this standard approach by, instead of directly computing Cartesian locations, expressing the original position problem as a system of distance-based constraints that are then solved using analytical and numerical procedures adapted to their particularities. In favor of developing the basics and theory of the proposed approach, this thesis focuses on the study of the most fundamental planar kinematic chains, namely, Baranov trusses, Assur kinematic chains, and pin-jointed Gr¨ubler kinematic chains. The results obtained have shown that the novel developed techniques are promising tools for the position analysis of kinematic chains and related problems. For example, using these techniques, the characteristic polynomials of most of the cataloged Baranov trusses can be obtained without relying on variable eliminations or trigonometric substitutions and using no other tools than elementary algebra. An outcome in clear contrast with the complex variable eliminations require when independent loop equations are used to tackle the problem. The impact of the above result is actually greater because it is shown that the characteristic polynomial of a Baranov truss, derived using the proposed distance-based techniques, contains all the necessary and sufficient information for solving the position

    Esta tesis aborda el problema de análisis de posición de cadenas cinemáticas, mecanismos con cuerpos rígidos (enlaces) interconectados por pares cinemáticos (articulaciones). Este problema, de naturaleza geométrica, consiste en encontrar los modos de ensamblaje factibles que una cadena cinemática puede adoptar. Un modo de ensamblaje es una transformación relativa posible entre los enlaces de una cadena cinemática. Los métodos reportados en la literatura para la solución del análisis de posición de cadenas cinemáticas se pueden clasificar como gráficos, analíticos o numéricos. Los enfoques gráficos son geométricos y se diseñan para resolver problemas particulares. Los métodos analíticos y numéricos tratan con cadenas cinemáticas de cualquier topología y traducen el problema geométrico original en un sistema de ecuaciones cinemáticas que define la ubicación de cada enlace, basado generalmente en ecuaciones de bucle independientes. En los enfoques analíticos, el sistema de ecuaciones cinemáticas se reduce a un polinomio, conocido como el polinomio característico de la cadena cinemática, utilizando diferentes métodos de eliminación. En los métodos numéricos, el sistema se resuelve utilizando, por ejemplo, la continuación polinomial o procedimientos basados en intervalos. En cualquier caso, el uso de ecuaciones de bucle independientes, un estándar en cinemática de mecanismos, rara vez ha sido cuestionado a pesar de que el sistema resultante de ecuaciones es bastante complicado, incluso para cadenas simples. Por otra parte, establecer el análisis de la posición de cadenas cinemáticas directamente en términos de poses, con o sin el uso de ecuaciones de bucle independientes, presenta dos inconvenientes: sistemas de referencia arbitrarios deben ser introducidos, y todas las fórmulas implican traslaciones y rotaciones de forma simultánea. Esta tesis se aparta de este enfoque estándar expresando el problema de posición original como un sistema de restricciones basadas en distancias, en lugar de directamente calcular posiciones cartesianas. Estas restricciones son posteriormente resueltas con procedimientos analíticos y numéricos adaptados a sus particularidades. Con el propósito de desarrollar los conceptos básicos y la teoría del enfoque propuesto, esta tesis se centra en el estudio de las cadenas cinemáticas planas más fundamentales, a saber, estructuras de Baranov, cadenas cinemáticas de Assur, y cadenas cinemáticas de Grübler. Los resultados obtenidos han demostrado que las técnicas desarrolladas son herramientas prometedoras para el análisis de posición de cadenas cinemáticas y problemas relacionados. Por ejemplo, usando dichas técnicas, los polinomios característicos de la mayoría de las estructuras de Baranov catalogadas se puede obtener sin realizar eliminaciones de variables o sustituciones trigonométricas, y utilizando solo álgebra elemental. Un resultado en claro contraste con las complejas eliminaciones de variables que se requieren cuando se utilizan ecuaciones de bucle independientes. El impacto del resultado anterior es mayor porque se demuestra que el polinomio característico de una estructura de Baranov, derivado con las técnicas propuestas, contiene toda la información necesaria y suficiente para resolver el análisis de posición de las cadenas cinemáticas de Assur que resultan de la sustitución de algunas de sus articulaciones de revolución por articulaciones prismáticas. De esta forma, se concluye que los polinomios de todos los robots planares totalmente paralelos se pueden derivar directamente del polinomio característico del conocido robot 3-RPR. Adicionalmente, se presenta un procedimiento eficaz, basado en restricciones de distancias y áreas orientadas, y argumentos geométricos, para trazar curvas de acoplador de cadenas cinemáticas de Grübler. En conjunto, todas estas técnicas y resultados constituyen contribuciones a la cinemática teórica de mecanismos, la cinemática de robots, y la geometría plana de distancias. Barcelona 13-

  • Planificación de Movimientos en Entornos Dinámicos o Inciertos Mediante la Coordinación de Métodos Aleatorios de Búsqueda y Funciones Armónicas  Open access

     Íñiguez Galvete, Pedro Jesus
    Defense's date: 2012-05-23
    Institute of Industrial and Control Engineering (IOC), Universitat Politècnica de Catalunya
    Theses

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    En los métodos planificadores de trayectorias basados en funciones potenciales, la utilización de las funciones armónicas tiene la importante propiedad de no presentar mínimos locales. Sin embargo, la creación de planificadores basados en estas funciones armónicas se ha encontrado con serias dificultades, sobre todo cuando el número de grados de libertad es elevado. Por este motivo, esta tesis realiza inicialmente un estudio de las propiedades más relevantes de dichas funciones armónicas; destacando aquellas que han sido la causa de su reducida aplicación en la generación de trayectorias. Al mismo tiempo, el resultado de este estudio sirve de base para la proposición de métodos compensatorios que permitan reducir las propiedades negativas de las funciones armónicas, como funciones potenciales aplicables a la generación de movimientos en robótica. Después se considera los métodos numéricos de cálculo de las funciones armónicas, así como el coste computacional de los mismos. Con el objetivo de reducir el tiempo de cálculo, esta tesis propone una discretización jerárquica y un método eficiente de etiquetado de celdas. Por su parte, dicha discretización jerárquica, se va realizando progresivamente mediante muestreo aleatorio y descomposición de celdas, lo que genera un escenario parcialmente conocido que, sin embargo, permitirá en cierto número de casos encontrar la trayectoria buscada. Por lo tanto, esta propuesta reduce drásticamente el número de puntos de cálculo y, por consiguiente, el tiempo de computación. La tesis completa la propuesta de un planificador combinando las técnicas de muestreo con el cálculo de funciones armónicas mediante un método de exploración aleatorio conducido (PHM), aplicado a un espacio de configuraciones discretizado jerárquicamente sobre el que se va recalculando la función armónica. De esta forma la exploración se guía hacia zonas más prometedoras, intentando obtener la solución por fases.

    In methods based trajectories planners potential functions, the use of harmonic functions has the important property of not presenting local minima. However, the creation of planners based on these harmonic functions has met with serious difficulties, especially when the number of degrees of freedom is high. For this reason, this thesis makes an initial study of the properties most relevant of these harmonic functions, highlighting those that have been the cause of their limited application in the generation of trajectories. At the same time, the result of this study provides a basis for proposing compensatory methods to reduce the negative properties of harmonic functions as potential functions applicable to the generation of robotic movements. Then we consider numerical methods for calculating the harmonic functions and the computational cost of the same. In order to reduce computation time, this thesis proposes a hierarchical discretization and an efficient method of labeling cells. Meanwhile, this discretization hierarchical be made gradually by random sampling and decomposition of cells, generating a scene partially known, however, allow a number of cases in finding the trajectory sought. Therefore, this proposal drastically reduces the number of calculation points, and hence the computation time. The thesis, complete a proposed planner combining sampling techniques to the calculation of harmonic functions by a method of random exploration conducted (PHM), applied to a hierarchically discretized configuration space on which the harmonic function is recalculated. In this way the exploration is guided to more promising, trying to obtain the solution phases.

  • Haptic guidance based on harmonic functions path planning for the teleoperation of robotic tasks

     Vázquez Hurtado, Carlos
    Defense's date: 2012-01-27
    Institute of Industrial and Control Engineering (IOC), Universitat Politècnica de Catalunya
    Theses

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  • Sincronización y teleoperación con interacción visual 3D de redes de manipuladores móviles y robots con articulaciones flexibles

     Mas Casals, Orestes Miquel; Rosell Gratacos, Joan; Nuño Ortega, Emmanuel; Palomo Avellaneda, Leopold; Flores Bazaldua, Ignacio; Beltran Guerrero, Diana Marcela; Perez Ruiz, Alexander; Basañez Villaluenga, Luis
    Participation in a competitive project

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  • Procedimiento de generación de un recorrido para una broncoscopia virtual

     Rosell Gratacos, Joan; Perez Ruiz, Alexander; Cabras, Paolo; Rosell Gratacos, Antoni
    Date of request: 2012-05-14
    Invention patent

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    Procedimiento y sistema de generación de un recorrido para una broncoscopia virtual, que comprende generar un modelo de un árbol traqueo-bronquial y un modelo de un broncoscopio. El modelo del árbol traqueo-bronquial comprende una representación de las paredes del árbol y de una zona objetivo. El modelo del broncoscopio comprende una representación de un extremo visor (punta) del broncoscopio mediante una cadena cinemática de cuerpos rígidos articulados entre sí. Los cuerpos rígidos comprenden al menos una base y un cuerpo visor. La rotación de las articulaciones representa un movimiento de flexión de la punta. El procedimiento comprende además calcular una secuencia de desplazamientos de la cadena que conduzca el cuerpo visor hacia el objetivo sin que ninguno de los cuerpos rígidos sobrepase las paredes del árbol traqueo-bronquial, siendo calculado cada tramo aplicando al menos un valor de rotación de las articulaciones de la cadena y un movimiento de avance de la cadena.

  • Procedimiento y sistema de generación de un recorrido para una broncoscopia virtual

     Rosell Gratacos, Joan; Cabras, Paolo; Perez Ruiz, Alexander; Rosell Gratacòs, Antoni
    Date of request: 2012-05-14
    Invention patent

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    Teleoperación de manos antropomorfas  Open access

     Suarez Feijoo, Raul; Rosell Gratacos, Joan; Colasanto, Luca
    Workshop Español de Robótica
    Presentation's date: 2011-11-28
    Presentation of work at congresses

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    Un escenario ideal para la teleoperaci´on de manos antropomorfas es que el operador humano pueda realizar una determinada operaci´on con sus propias manos y el sistema rob´otico teleoperado provisto de una mano antropomorfa la replique. Actualmente ya existen manos mec´anicas antropomorfas con numerosos grados de libertad y la posibilidad de dirigir sus acciones de forma remota es viable, pero, sin embargo, la imposibilidad de que la cinem´atica de la mano rob´otica sea totalmente equivalente a la de cualquier humano genera un problema significativo en el esquema de teleoperaci´on mencionado. La respuesta a c´omo se deben reproducir los movimientos de la mano humana en la mano rob´otica para que ´esta realice la misma tarea no es lo evidente que en principio pudiera parecer. En este contexto, este art´ıculo presenta dos proyecciones de movimientos de la mano humana a la mano rob´otica que tienen como fin facilitar las tareas de telemanipulaci ´on. Ambas proyecciones han sido implementadas y en el art´ıculo se incluyen ejemplos de resultados experimentales.

  • Importance Sampling based on Adaptive Principal Component Analysis

     Rosell Gratacos, Joan; Cruz, Luis; Perez Ruiz, Alexander; Suarez Feijoo, Raul
    IEEE International Symposium on Assembly and Manufacturing
    Presentation's date: 2011-05
    Presentation of work at congresses

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    Sampling-based approaches are currently the most efficient ones to solve path planning problems, being their performance dependant on the ability to generate samples in those areas of the configuration space relevant to the problem. This paper introduces a novel importance sampling method that uses Principal Component Analysis to focalize the region where to sample in order to increase the probability of finding collision-free configurations. The proposal is illustrated with a 2D configuration space with a narrow passage and compared to the uniform random sampling method.

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    Planificación de movimientos para conjuntos mano-brazo con numerosos grados de libertad  Open access

     Suarez Feijoo, Raul; Rosell Gratacos, Joan
    Workshop Español de Robótica
    Presentation's date: 2011-11-28
    Presentation of work at congresses

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    Con el objetivo de avanzar hacia la emulaci ´on de las capacidades y destreza de la mano humana se est ´an desarrollando manos rob´oticas con prestaciones muy superiores a las tradicionales pinzas usadas en la rob´otica industrial. El uso de estas manos rob´oticas conlleva asociados nuevos retos, y entre ellos est ´a el de la planificaci ´on eficiente de sus movimientos, ya que aunque algunos m´etodos de planificaci ´on tradiciones podr´ıan ser v´alidos, su aplicaci ´on pr´actica es limitada debido sobre todo al elevado n´umero de grados de libertad que tiene un sistema rob´otico que incluya una mano antropomorfa montada sobre un brazo manipulador. Este art´ıculo presenta un enfoque que permite soluciones suficientemente eficientes para ser utilizadas en la pr´actica. El enfoque propuesto est ´a basado en la reducci ´on de la dimensi ´on del espacio de b´usqueda y en la utilizaci ´on de t´ecnicas de muestreo para generar movimientos del conjunto mano-brazo en entornos con obst ´aculos que pueden imponer fuertes restricciones en la b´usqueda de movimientos sin colisi ´on, como sucede normalmente cuando la mano se acerca a un objeto para su sujeci ´on y manipulaci ´on. Los desarrollos te´oricos han sido implementados tanto en simulaci ´on como en un sistema f´ısico real, por lo que se incluyen resultados experimentales reales.

  • Including virtual constraints in motion planning for anthropomorphic hands

     Rosell Gratacos, Joan; Suarez Feijoo, Raul; Perez Ruiz, Alexander; Rosales Gallegos, Carlos
    IEEE International Symposium on Assembly and Manufacturing
    Presentation's date: 2011-05
    Presentation of work at congresses

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    This paper copes with the problem of finding a collision-free path for a hand-arm robotic system from an initial unconstrained configuration to a final grasping (or preshape) one. The aim is to obtain a natural motion as a sequence of human-like postures that both capture the coupling that there exist between the fingers of the human hand and also maintain the palm oriented towards the object to be grasped. The proposed method is a sampling-based approach whose efficiency relies in the reduction of the dimensionality obtained by considering, for the finger joints, a subspace determined by the main principal motion directions that capture the coupling and, for the position and orientation of the palm, the submanifold that satisfies the orientation constraint. The approach is illustrated with an example and compared to the case where no virtual constrains are used, validating the proposal.

  • Haptic-based navigation for the virtual bronchoscopy

     Cabras, Paolo; Rosell Gratacos, Joan; Perez Ruiz, Alexander; Aguilar, Wilbert G.; Rosell, Antoni
    World Congress of the International Federation of Automatic Control
    Presentation's date: 2011-08
    Presentation of work at congresses

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    A framework for robotized teleoperated tasks  Open access  awarded activity

     Basañez Villaluenga, Luis; Rosell Gratacos, Joan; Palomo Avellaneda, Leopold; Nuño, Emmanuel; Portilla, Henry
    Workshop Español de Robótica
    Presentation's date: 2011-11-28
    Presentation of work at congresses

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    Teleoperation systems allow the extension of the human operator’s sensing and manipulative capability into a remote environment to perform tasks at a distance, but the time-delays in the communications affect the stability and transparency of such systems. This work presents a teleoperation framework in which some novel tools, such as nonlinear controllers, relational positioning techniques, haptic guiding and augmented reality, are used to increase the sensation of immersion of the human operator in the remote site. Experimental evidence supports the advantages of the proposed framework.

    "Premio al mejor artículo presentado en ROBOT 2011" atorgat pel Grupo de Robótica, Visión y Control de la Universidad de Sevilla, la Universidad Pablo Olavide i el Centro Avanzado de Tecnologías Aeroespaciales.

  • An assisted re-synchronization method for robotic teleoperated tasks

     Perez Ruiz, Alexander; Rosell Gratacos, Joan
    IEEE International Conference on Robotics and Automation
    Presentation's date: 2011-05
    Presentation of work at congresses

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    Teleoperation tasks are performed at cartesian evel when the robot and the haptic device ave dissimilar inematics. If the size of the workspaces is also dissimilar, as it is usually the case, the mapping between workspaces must e handled with care in order to let the user teleoperate the obot in a natural and precise way. This paper formulates the apping of workspaces based on the re-synchronization method nd proposes an assisted system that lightens the user from the edious part of the method, by guiding him/her towards the est re-synchronization position, thus minimizing the number of jumps. The proposal is part of a teleoperated guiding system being developed by the authors.

    Postprint (author’s final draft)

  • Autonomous motion planning of a hand-arm robotic system based on captured human-like hand postures

     Rosell Gratacos, Joan; Suarez Feijoo, Raul; Rosales Gallegos, Carlos; Perez Ruiz, Alexander
    Autonomous robots
    Date of publication: 2011-07
    Journal article

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    The paper deals with the problem of motion planning of anthropomorphic mechanical hands avoiding collisions and trying to mimic real human hand postures. The approach uses the concept of “principal motion directions” to reduce the dimension of the search space in order to obtain results with a compromise between motion optimality and planning complexity (time). Basically, the work includes the following phases: capturing the human hand workspace using a sensorized glove and mapping it to the mechanical hand workspace, reducing the space dimension by looking for the most relevant principal motion directions, and planning the hand movements using a probabilistic roadmap planner. The approach has been implemented for a four finger anthropomorphic mechanical hand (17 joints with 13 independent degrees of freedom) assembled on an industrial robot (6 independent degrees of freedom), and experimental examples are included to illustrate its validity.

  • Haptic Primitives Guidance Based on the Kautham Path Planner

     Vázquez, Carlos; Rosell Gratacos, Joan; Chirinos, Luis; Domínguez, Omar
    IEEE/RSJ International Conference on Intelligent Robots and Systems
    Presentation's date: 2010-10-18
    Presentation of work at congresses

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    Path planning methods are well suited to automatically perform robotic tasks; haptic guidance is a powerful tool for disabled people rehabilitation, sports training, handcraft skills acquiring and such kind of enactive tasks. This paper proposes a novel an efficient method to accomplish guided movements by efficiently combing path planning methods and haptic guidance. The main contribution of this paper is the development of a reliable method to haptically guide the user within a virtual robotic task, by means of: on-line, collision free, path planning generated trajectories. To accomplish haptic guidance three stages must be correctly done: the first one where the user selects the desired objects and obstacles within a virtual environment to set up the task, the second one, where a path planner looks for the task trajectory and, the third one, where the user is constrained to on-line generated local channels and solution paths that offer a reliable path guidance system to achieve the task movements.

    Postprint (author’s final draft)

  • Automatic determination of fixturing points: quality analysis for different number of points and friction values

     Rosell Gratacos, Joan; Suarez Feijoo, Raul; Penalba, Francesc
    Date of publication: 2010-09-01
    Book chapter

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  • Robust perceptual organization techniques for analysis of color images  Open access

     Moreno Serrano, Rodrigo
    Defense's date: 2010-11-15
    Institute of Industrial and Control Engineering (IOC), Universitat Politècnica de Catalunya
    Theses

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    Esta tesis aborda el desarrollo de nuevas técnicas de análisis robusto de imágenes estrechamente relacionadas con el comportamiento del sistema visual humano. Uno de los pilares de la tesis es la votación tensorial, una técnica robusta que propaga y agrega información codificada en tensores mediante un proceso similar a la convolución. Su robustez y adaptabilidad han sido claves para su uso en esta tesis. Ambas propiedades han sido verificadas en tres nuevas aplicaciones de la votación tensorial: estimación de estructura, detección de bordes y segmentación de imágenes adquiridas mediante estereovisión.El mayor problema de la votación tensorial es su elevado coste computacional. En esta línea, esta tesis propone dos nuevas implementaciones eficientes de la votación tensorial derivadas de un análisis en profundidad de esta técnica.A pesar de su capacidad de adaptación, esta tesis muestra que la formulación original de la votación tensorial (a partir de aquí, votación tensorial clásica) no es adecuada para algunas aplicaciones, dado que las hipótesis en las que se basa no se ajustan a todas ellas. Esto ocurre particularmente en el filtrado de imágenes en color. Así, esta tesis muestra que, más que un método, la votación tensorial es una metodología en la que la codificación y el proceso de votación pueden ser adaptados específicamente para cada aplicación, manteniendo el espíritu de la votación tensorial.En esta línea, esta tesis propone un marco unificado en el que se realiza a la vez el filtrado de imágenes y la detección robusta de bordes. Este marco de trabajo es una extensión de la votación tensorial clásica en la que el color y la probabilidad de encontrar un borde en cada píxel se codifican mediante tensores, y en el que el proceso de votación se basa en un conjunto de criterios perceptuales relacionados con el modo en que el sistema visual humano procesa información. Los avances recientes en la percepción del color han sido esenciales en el diseño de dicho proceso de votación.Este nuevo enfoque ha sido efectivo, obteniendo excelentes resultados en ambas aplicaciones. En concreto, el nuevo método aplicado al filtrado de imágenes tiene un mejor rendimiento que los métodos del estado del arte para ruido real. Esto lo hace más adecuado para aplicaciones reales, donde los algoritmos de filtrado son imprescindibles. Además, el método aplicado a detección de bordes produce resultados más robustos que las técnicas del estado del arte y tiene un rendimiento competitivo con relación a la completitud, discriminabilidad, precisión y rechazo de falsas alarmas.Además, esta tesis demuestra que este nuevo marco de trabajo puede combinarse con otras técnicas para resolver el problema de segmentación robusta de imágenes. Los tensores obtenidos mediante el nuevo método se utilizan para clasificar píxeles como probablemente homogéneos o no homogéneos. Ambos tipos de píxeles se segmentan a continuación por medio de una variante de un algoritmo eficiente de segmentación de imágenes basada en grafos. Los experimentos muestran que el algoritmo propuesto obtiene mejores resultados en tres de las cinco métricas de evaluación aplicadas en comparación con las técnicas del estado del arte, con un coste computacional competitivo.La tesis también propone nuevas técnicas de evaluación en el ámbito del procesamiento de imágenes. En concreto, se proponen dos métricas de filtrado de imágenes con el fin de medir el grado en que un método es capaz de preservar los bordes y evitar la introducción de defectos. Asimismo, se propone una nueva metodología para la evaluación de detectores de bordes que evita posibles sesgos introducidos por el post-procesado. Esta metodología se basa en cinco métricas para estimar completitud, discriminabilidad, precisión, rechazo de falsas alarmas y robustez. Por último, se proponen dos nuevas métricas no paramétricas para estimar el grado de sobre e infrasegmentación producido por los algoritmos de segmentación de imágenes.

    This thesis focuses on the development of new robust image analysis techniques more closely related to the way the human visual system behaves. One of the pillars of the thesis is the so called tensor voting technique. This is a robust perceptual organization technique that propagates and aggregates information encoded by means of tensors through a convolution like process. Its robustness and adaptability have been one of the key points for using tensor voting in this thesis. These two properties are verified in the thesis by applying tensor voting to three applications where it had not been applied so far: image structure estimation, edge detection and image segmentation of images acquired through stereo vision.The most important drawback of tensor voting is that its usual implementations are highly time consuming. In this line, this thesis proposes two new efficient implementations of tensor voting, both derived from an in depth analysis of this technique.Despite its adaptability, this thesis shows that the original formulation of tensor voting (hereafter, classical tensor voting) is not adequate for some applications, since the hypotheses from which it is based are not suitable for all applications. This is particularly certain for color image denoising. Thus, this thesis shows that, more than a method, tensor voting can be thought of as a methodology in which the encoding and voting process can be tailored for every specific application, while maintaining the tensor voting spirit.By following this reasoning, this thesis proposes a unified framework for both image denoising and robust edge detection.This framework is an extension of the classical tensor voting in which both color and edginess the likelihood of finding an edge at every pixel of the image are encoded through tensors, and where the voting process takes into account a set of plausible perceptual criteria related to the way the human visual system processes visual information. Recent advances in the perception of color have been essential for designing such a voting process.This new approach has been found effective, since it yields excellent results for both applications. In particular, the new method applied to image denoising has a better performance than other state of the art methods for real noise. This makes it more adequate for real applications, in which an image denoiser is indeed required. In addition, the method applied to edge detection yields more robust results than the state of the art techniques and has a competitive performance in recall, discriminability, precision, and false alarm rejection.Moreover, this thesis shows how the results of this new framework can be combined with other techniques to tackle the problem of robust color image segmentation. The tensors obtained by applying the new framework are utilized to classify pixels into likely homogeneous and likely inhomogeneous. Those pixels are then sequentially segmented through a variation of an efficient graph based image segmentation algorithm. Experiments show that the proposed segmentation algorithm yields better scores in three of the five applied evaluation metrics when compared to the state of the art techniques with a competitive computational cost.This thesis also proposes new evaluation techniques in the scope of image processing. First, two new metrics are proposed in the field of image denoising: one to measure how an algorithm is able to preserve edges, and the second to measure how a method is able not to introduce undesirable artifacts. Second, a new methodology for assessing edge detectors that avoids possible bias introduced by post processing is proposed. It consists of five new metrics for assessing recall, discriminability, precision, false alarm rejection and robustness. Finally, two new non parametric metrics are proposed for estimating the degree of over and undersegmentation yielded by image segmentation algorithms.

  • DESARROLLO DE SISTEMAS DE GULADIO EN LA BRONCOSCOPIA(GUIBROD) PARA EL DIAGNÓSTICO DEL NÓDULO PULMONAR PERIFÉRICO

     Basañez Villaluenga, Luis; Suarez Feijoo, Raul; Riego Pérez, Albert; Perez Ruiz, Alexander; Rosell Gratacos, Joan
    Participation in a competitive project

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  • Sampling-based path planning for geometrically-constrained objects

     Rodriguez Tsouroukdissian, Adolfo; Perez Ruiz, Alexander; Rosell Gratacos, Joan; Basañez Villaluenga, Luis
    IEEE International Conference on Robotics and Automation
    Presentation's date: 2009-05
    Presentation of work at congresses

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    Efficient search of obstacle-free paths for anthropomorphic hands  Open access

     Suarez Feijoo, Raul; Rosell Gratacos, Joan; Perez Ruiz, Alexander; Rosales Gallegos, Carlos
    IEEE/RSJ International Conference on Intelligent Robots and Systems
    Presentation's date: 2009-10-12
    Presentation of work at congresses

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    The planning of collision-free motions of a handarm system to reach a grasp or preshape configuration is not a simple issue due to the high number of involved degrees of freedom. This paper presents an efficient sampling-based path planner that copes with this issue by considering a reduced search space. The dimension of this space is not fixed but it is iteratively increased according to the difficulty of the task at hand. Initially the search space is 1-dimensional along the line defined by the initial and goal hand configurations (by construction those configurations always belong to the search space), and then its dimension is increased by iteratively adding principal motion directions (that couple the finger motions), trying in this way to produce hand movements through anthropomorphic natural postures.

  • TELETAREA ROBOTIZADA COOPERATIVA EN RED

     Nuño Ortega, Emmanuel; Ayza Graells, Jordi; Palomo Avellaneda, Leopold; Flores Bazaldua, Ignacio; Rodriguez Tsouroukdissian, Adolfo; Rosell Gratacos, Joan; Riego Pérez, Albert; Basañez Villaluenga, Luis
    Participation in a competitive project

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  • A constraint-based probabilistic roadmap planner

     Perez Ruiz, Alexander; Rodríguez, A; Rosell Gratacos, Joan; Basañez Villaluenga, Luis
    40th International Symposium on Robotics
    Presentation's date: 2009-03-10
    Presentation of work at congresses

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  • Analysis of fixturing quality for a variable number of fixturing points and friction values

     Penalba, Francesc; Rosell Gratacos, Joan; Suarez Feijoo, Raul
    IEEE International Symposium on Assembly and Manufacturing
    Presentation's date: 2009-11-17
    Presentation of work at congresses

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    Motion planning for high DOF anthropomorphic hands  Open access

     Rosell Gratacos, Joan; Suarez Feijoo, Raul; Rosales Gallegos, Carlos; Garcia, Jorge Alberto; Perez Ruiz, Alexander
    IEEE International Conference on Robotics and Automation
    Presentation's date: 2009
    Presentation of work at congresses

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    The paper deals with the problem of motion planning of anthropomorphic mechanical hands avoiding collisions. The proposed approach tries to mimic the real human hand motions, but reducing the dimension of the search space in order to obtain results as a compromise between motion optimality and planning complexity (time) by means of the concept of principal motion directions. Basically, the work includes the following phases: capturing the human hand workspace using a sensorized glove and mapping it to the mechanical hand workspace, reducing the space dimension by looking for the most relevant principal motion directions, and planning the hand movements using a sampling-based roadmap planner. The approach has been implemented for a four finger anthropomorphic mechanical hand, and some examples are included to illustrate its validity.

  • Path planning using sub- and super-harmonic functions

     Iñiguez, Pedro; Rosell Gratacos, Joan
    40th International Symposium on Robotics
    Presentation's date: 2009-03-10
    Presentation of work at congresses

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  • A roadmap to robot motion planning software development

     Perez Ruiz, Alexander; Rosell Gratacos, Joan
    Computer applications in engineering education
    Date of publication: 2009-02-23
    Journal article

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  • Planificación de movimientos en robótica: curso práctico para implementar un PRM

     Perez Ruiz, Alexander; Rosell Gratacos, Joan
    Jornadas de Automática
    Presentation of work at congresses

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  • Influence of the sampling strategy on the incremental generation of the grasp space

     Roa, M; Suarez Feijoo, Raul; Rosell Gratacos, Joan
    11th International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines, CLAWAR 2008
    Presentation's date: 2008-09-08
    Presentation of work at congresses

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  • Grasp Space Generation Using Sampling and Computation of Independent Regions

     Roa, M; Suarez Feijoo, Raul; Rosell Gratacos, Joan
    IEEE/RSJ International Conference on Intelligent Robots and Systems
    Presentation's date: 2008-06-22
    Presentation of work at congresses

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  • Exploration of the grasp space using independent contact and non-graspable regions

     Roa, Máximo; Suarez Feijoo, Raul; Rosell Gratacos, Joan
    Date: 2008-04
    Report

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  • Efficient motion planning for high DOF hands using principal motion directions.

     Rosell Gratacos, Joan; Suarez Feijoo, Raul; Rosales, C; García, J A and A Pérez
    Date: 2008-10
    Report

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  • Motion Planning for Haptic Guidance

     Rosell Gratacos, Joan; Vázquez, C; Perez Ruiz, Alexander; Iñiguez, Pedro
    Journal of intelligent and robotic systems
    Date of publication: 2008-11
    Journal article

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  • Motion Planning for Haptic Guidance

     Rosell Gratacos, Joan; Vázquez, Carlos; Perez Ruiz, Alexander; Iñiguez, Pedro
    Journal of intelligent and robotic systems: theory and applications (Online)
    Date of publication: 2008-05
    Journal article

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  • A General Deterministic Sequence for Sampling d-Dimensional Configuration Spaces

     Rosell Gratacos, Joan; Roa, Máximo; Perez Ruiz, Alexander; García, Fernando
    Journal of intelligent and robotic systems
    Date of publication: 2007-07
    Journal article

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  • A performance analysis tool of discrete-events systems

     Peñarroya, A; Casado, F; Rosell Gratacos, Joan
    Date: 2007-01
    Report

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    A novel path planning proposal based on the combination of deterministic sampling and harmonic functions  Open access

     Rosell Gratacos, Joan; Vázquez, C; Pérez, A; Iñíguez, P
    Date: 2007-03
    Report

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    The sampling-based approach is currently the most successful and yet more promising approach to path planning problems. Sampling-based methods are demonstrated to be probabilistic complete, being their performance reliant on the generation of samples. To obtain a good set of samples, this paper proposes a new sampling paradigm based on deterministic sampling paradigm based on a deterministic sampling sequence guided by an harmonic potential function computed on a hierarchical cell decomposition of C-space. In the proposed method, known as Kautham sampler, samples are not isolated configurations but parts of a whole. As samples are generated they are dynamically grouped into cells that capture the C-space structure. This allows the use of harmonic functions to share information and guide further sampling towards more promising regions of C-space. Finally, using the samples obtained, a roadmap is easily built taking advantage of the known neighbourhood relationships.