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  • Stability of nonlinear teleoperators using PD controllers without velocity measurements

     Nuño, Emmanuel; Basañez Villaluenga, Luis; Lopez Franco, Carlos; Arana Daniel, Nancy
    Journal of the Franklin Institute
    Date of publication: 2014-01
    Journal article

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    This paper presents two Proportional-Derivative (PD) like controllers for nonlinear bilateral teleoperation systems. Compared to previous controllers of this kind, these schemes do not make use of velocity measurements. Under the assumptions that the human operator and the environment define passive maps from velocity to force, both controllers can ensure boundedness of velocities and position error. Moreover, in the case that the human and environment forces are zero, the controllers ensure velocity and position synchronization. Furthermore, the paper also presents a generalization to the case of teleoperation of networks of multiple robots. Simulations and real experiments, comparing the performance on free motion and interacting with a stiff wall, support the performance of the reported schemes. The experiments have been performed using two 3-degree-of-freedom nonlinear manipulators.

  • Operational space consensus in networks of robots: The leader-follower case

     Aldana Lopez, Carlos Ivan; Romero, Eduardo; Nuño, Emmanuel; Basañez Villaluenga, Luis
    Date of publication: 2013-12-26
    Book chapter

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  • Leader-follower and leaderless consensus in networks of flexible-joint manipulators

     Nuño, Emmanuel; Valle, Daniela; Sarras, Ioannis; Basañez Villaluenga, Luis
    Congreso Nacional de la Asociación Mexicana de Control Automático
    Presentation's date: 2013-10-16
    Presentation of work at congresses

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  • Consensus of networks of nonidentical robots with flexible joints, variable time--delays and unmeasurable velocities

     Valle, Daniela; Nuño, Emmanuel; Basañez Villaluenga, Luis; Arana Daniel, Nancy
    IEEE/RSJ International Conference on Intelligent Robots and Systems
    Presentation's date: 2013-11-06
    Presentation of work at congresses

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    The present paper proposes two controllers for solving a consensus problem to a given desired position of networks composed of a class of under actuated mechanical systems: flexible joints robots. One of the controllers makes use of joint (motor) velocity signals while the other only uses joint positions. The only assumption on the directed and weighted interconnection graph is that it is connected. Further, the interconnection may induce variable time¿delays. The paper presents some experiments, using three 3-Degrees of Freedom manipulators, which show the performance of the proposed approaches.

  • Bilateral teleoperation of flexible-joint manipulators with dynamic gravity compensation and variable time-delays

     Nuño, Emmanuel; Valle, Daniela; Sarras, Ioannis; Basañez Villaluenga, Luis
    IEEE/RSJ International Conference on Intelligent Robots and Systems
    Presentation's date: 2013-11-06
    Presentation of work at congresses

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    It is widely known that the problem of controlling a rigid bilateral teleoperator with time-delays has been effectively addressed since the late 80¿s. However, the control of flexible joint manipulators in a bilateral teleoperation scenario, with dynamic gravity compensation, remains an open problem. This work aims at filling this gap by presenting a new controller for bilateral teleoperators composed of a rigid local manipulator and a flexible-joint remote manipulator with dynamic gravity compensation and asymmetric variable timedelays in the communication channel. In order to dynamically compensate the gravity term, in the flexible joint manipulator, a change of coordinates which accounts for the joint and link gravity position drift is used. The rest of the controller is a simple PD scheme. Assuming that the human operator and the environment define passive maps from velocity to force, it is proved that velocities and local and remote position errors are bounded. Additionally, if the human operator and remote environment forces are zero then velocities asymptotically converge to zero and position tracking is established. Some simulations are presented in order to show the performance of the proposed controllers.

  • Control of bilateral teleoperators in operational space without velocity measurements

     Aldana Lopez, Carlos Ivan; Nuño, Emmanuel; Basañez Villaluenga, Luis
    IEEE/RSJ International Conference on Intelligent Robots and Systems
    Presentation's date: 2013-11-06
    Presentation of work at congresses

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    This paper proposes a proportional plus damping injection (P + d) controller for bilateral teleoperators in the operational space. Unit quaternions are used to describe the endeffectors¿ orientation since they exhibit the well known property of being a singularity-free representation. The proposed controller does not need the measurement of the velocities, instead a passivity¿based filter is used. Under the reasonable assumptions that the human operator and the environment define passive maps from force to velocity, it is proved that velocities and pose (position and orientation) errors between the local and the remote manipulators are bounded. Moreover, in the case that the human and the environment forces are zero, the velocities and pose errors converge asymptotically to zero. Finally, experimental validation using two robots of 6-Degreesof- Freedom (DoF) shows the effectiveness of the proposed control scheme.

  • Consensus of networks of nonidentical robots with flexible joints, variable time-delays and immeasurable velocities

     Valle, Daniela; Nuño, Emmanuel; Basañez Villaluenga, Luis; Arana Daniel, Nancy
    IEEE/RSJ International Conference on Intelligent Robots and Systems
    Presentation of work at congresses

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    The present paper proposes two controllers for solving a consensus problem to a given desired position of networks composed of a class of under actuated mechanical systems: flexible joints robots. One of the controllers makes use of joint (motor) velocity signals while the other only uses joint positions. The only assumption on the directed and weighted interconnection graph is that it is connected. Further, the interconnection may induce variable time-delays. The paper presents some experiments, using three 3-Degrees of Freedom manipulators, which show the performance of the proposed approaches.

  • Modeling non-linear viscoelastic behavior under large deformations

     del Castillo Pérez, Esteban; Basañez Villaluenga, Luis; Gil Dolcet, Ernest
    International journal of non-linear mechanics
    Date of publication: 2013-12
    Journal article

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    This paper addresses the accurate modeling of the behavior of a thin layer of natural rubber subjected to large deformations. Such a system presents a non-linear viscoelastic behavior similar to many biological soft tissues. The proposed model uses an spring-mass system, and considers a non-linear evolution of the reaction forces of the membrane, as well as viscous and Coulomb friction. In the model, the elasticity coefficient of the springs has an exponential dependence of its elongation. Three experimental tests validate the proposed model, which reaches a real-time performance using an implicit integrator.

    This paper addresses the accurate modeling of the behavior of a thin layer of natural rubber subjected to large deformations. Such a system presents a non-linear viscoelastic behavior similar to many biological soft tissues. The proposed model uses an spring-mass system, and considers a non-linear evolution of the reaction forces of the membrane,as well as viscous and Coulomb friction. In the model, the elasticity coefficient of the springs has an exponential dependence of its elongation. Three experimental tests validate the proposed model, which reaches a real-time performance using an implicit integrator

  • Networking improves robustness in flexible-joint multi-robot systems with only joint position measurements

     Nuño, Emmanuel; Ortega, Romeo; Jayawardhana, Bayu; Basañez Villaluenga, Luis
    European journal of control
    Date of publication: 2013-12
    Journal article

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    This paper studies the robustness in the coordination - via energy-shaping - of multiple nonidentical flexible-joint robots with only joint position measurements. The control objective is to drive all manipulators link positions to the same constant equilibrium. If the physical parameters are exactly known, then a classical decentralized energy-shaping controller solves the desired control objective. However, under parameter uncertainty, the globally asymptotically stable equilibrium point is shifted away from the desired value. The main contribution of the paper is to show that the steady-state performance is improved adding to the decentralized control policy information exchange between the agents. More precisely, it is proven that the equilibrium with the networked controller is always closer (in a suitable metric) to the desired one than that using the decentralized controller, provided the communication graph representing the network is undirected and connected. This result holds globally for sufficiently large interconnection gains and locally (in a suitably defined sense) for all values of the gains. An additional advantage of networking is that the asymptotic stabilization objective can be achieved injecting lower gains into the loop. The paper also provides simulation and experimental evidence, which illustrate the fact that networking improves robustness with respect to parameter uncertainty.

  • Coordination of multi-agent Euler-Lagrange systems via energy-shaping: Networking improves robustness

     Nuño, Emmanuel; Ortega, Romeo; Jayawardhana, Bayu; Basañez Villaluenga, Luis
    Automatica
    Date of publication: 2013-10-01
    Journal article

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    In this paper, the robust coordination of multi-agent systems via energy-shaping is studied. The agents are nonidentical, Euler¿Lagrange systems with uncertain parameters which are regulated (with and without exchange of information between the agents) by the classical energy-based controller where the potential energy function is shaped such that, if the parameters are known, all agents converge globally to the same desired constant equilibrium. Under parameter uncertainty, the globally asymptotically stable (GAS) equilibrium point is shifted away from its desired value and this paper shows that adding information exchange between the agents to the decentralized control policy improves the steady-state performance. More precisely, it proves that if the undirected communication graph is connected, the equilibrium of the networked controller isalways closer (in a suitable metric) to the desired one than that of the decentralized controller. The result holds for all interconnection gains if the potential energy functions are quadratic, else, it is true for sufficiently large gains. An additional advantage of networking is that the asymptotic stabilization objective can be achieved by using lower gains into the loop. Some experimental results (using two nonlinear manipulators) given support to the main results of the paper

  • Consensus in networks of nonidentical Euler-Lagrange systems using P plus d controllers

     Nuño, Emmanuel; Sarras, Ioannis; Basañez Villaluenga, Luis
    IEEE transactions on robotics
    Date of publication: 2013-12
    Journal article

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    This paper presents a proportional plus damping controller that can asymptotically drive a network composed of N nonidentical Euler-Lagrange (EL) systems toward a consensus point. The agents can be fully actuated or can belong to a class of underactuated EL-systems. The network is modeled as a weighted and undirected static interconnection graph that can exhibit asymmetric variable time delays. Simulations, using a network with ten EL-systems, are reported to support the theoretical contributions of this study.

  • Grasp plannind under task-specific contact constraints  Open access

     Rosales Gallegos, Carlos José
    Defense's date: 2013-01-10
    Institute of Industrial and Control Engineering (IOC), Universitat Politècnica de Catalunya
    Theses

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    Several aspects have to be addressed before realizing the dream of a robotic hand-arm system with human-like capabilities, ranging from the consolidation of a proper mechatronic design, to the development of precise, lightweight sensors and actuators, to the efficient planning and control of the articular forces and motions required for interaction with the environment. This thesis provides solution algorithms for a main problem within the latter aspect, known as the {\em grasp planning} problem: Given a robotic system formed by a multifinger hand attached to an arm, and an object to be grasped, both with a known geometry and location in 3-space, determine how the hand-arm system should be moved without colliding with itself or with the environment, in order to firmly grasp the object in a suitable way. Central to our algorithms is the explicit consideration of a given set of hand-object contact constraints to be satisfied in the final grasp configuration, imposed by the particular manipulation task to be performed with the object. This is a distinguishing feature from other grasp planning algorithms given in the literature, where a means of ensuring precise hand-object contact locations in the resulting grasp is usually not provided. These conventional algorithms are fast, and nicely suited for planning grasps for pick-an-place operations with the object, but not for planning grasps required for a specific manipulation of the object, like those necessary for holding a pen, a pair of scissors, or a jeweler's screwdriver, for instance, when writing, cutting a paper, or turning a screw, respectively. To be able to generate such highly-selective grasps, we assume that a number of surface regions on the hand are to be placed in contact with a number of corresponding regions on the object, and enforce the fulfilment of such constraints on the obtained solutions from the very beginning, in addition to the usual constraints of grasp restrainability, manipulability and collision avoidance. The proposed algorithms can be applied to robotic hands of arbitrary structure, possibly considering compliance in the joints and the contacts if desired, and they can accommodate general patch-patch contact constraints, instead of more restrictive contact types occasionally considered in the literature. It is worth noting, also, that while common force-closure or manipulability indices are used to asses the quality of grasps, no particular assumption is made on the mathematical properties of the quality index to be used, so that any quality criterion can be accommodated in principle. The algorithms have been tested and validated on numerous situations involving real mechanical hands and typical objects, and find applications in classical or emerging contexts like service robotics, telemedicine, space exploration, prosthetics, manipulation in hazardous environments, or human-robot interaction in general.

  • 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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  • Bilateral Teleoperation of Cooperative Manipulators

     Aldana, Carlos; Basañez Villaluenga, Luis
    IEEE International Conference on Robotics and Automation
    Presentation's date: 2012
    Presentation of work at congresses

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    This paper presents an adaptive controller for the bilateral teleoperation of a system composed by a single local manipulator and multiple cooperative remote manipulators handling a common object. First, the nonlinear operational space dynamical behavior of the complete teleoperation system is derived. Then, under the assumptions that the remote manipulators are rigidly grasping a non-deformable object and that the communications may induce constant time-delays, it is proved that velocities and position-orientation error between the local manipulator end-effector and the object asymptotically converge to zero. Simulations results are included to show the effectiveness of the proposed approach.

  • Coordination of multi-agent systems via energy¿shaping: networking improves robustness

     Nuño Ortega, Emmanuel; Ortega, Romeo; Jayawardhana, Bayu; Basañez Villaluenga, Luis
    IFAC Workshop on Lagrangian and Hamiltonian Methods for Non Linear Control
    Presentation's date: 2012-08-29
    Presentation of work at congresses

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    In this paper the problem of robust coordination of multi–agent systems via energy–shaping is studied. The agents are nonidentical, Euler–Lagrange systems with uncertain parameters. The control objective is to drive all agents states to the same constant equilibrium— which is achieved shaping their potential energy function. It is assumed that, if the parameters are known, this task can be accomplished with a decentralized strategy. In the face of parameter uncertainty, the assigned equilibrium is shifted away from its desired value. It is shown that adding information exchange between the agents to this decentralized control policy improves the performance. More precisely, it is proven that if the communication graph is undirected and connected, the equilibrium of the networked controller is always closer (in a suitable metric) to the desired one. If the the potential energy functions are quadratic, the result holds for all interconnection gains, else, it is true for sufficiently large gains. The decentralized controller is the well–known energy–shaping proportional plus derivative controller, extensively used in applications. An additional advantage of networking is that the control objective is achieved injecting lower gains into the loop.

  • An adaptive controller for bilateral teleoperators: transatlantic experiments using the internet

     Nuño, Emmanuel; Basañez Villaluenga, Luis; de Alba Padilla, Carlos; López Franco, Carlos
    World Automation Congress
    Presentation's date: 2012-06-25
    Presentation of work at congresses

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    A bilateral teleoperator is composed of a local and a remote manipulators interconnected through a communication channel. A human operator interacts with the local manipulator to remotely execute a given task via the remote manipulator and the interaction of the remote manipulator with the remote environment is reflected back to the human operator. Thus, the control objective is to establish local and remote position synchronization. This paper employs adaptive control techniques, that can achieve the desired control objective, to an experimental setup composed of two nonlinear manipulators. In these novel experimental results the local and remote manipulators are located in Guadalajara, Mexico, and in Barcelona, Spain, respectively. The manipulators are two Sensable's PHANToM Omni® devices and are interconnected through the Internet. It is shown, experimentally, that the adaptive controllers provide asymptotic stability of the local and remote position error even in the presence of variable timedelays.

  • Output-feedback control of nonlinear bilateral teleoperators

     Sarras, Ioannis; Nuño, Emmanuel; Kinnaert, Michel; Basañez Villaluenga, Luis
    American Control Conference
    Presentation's date: 2012
    Presentation of work at congresses

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    The output-feedback design problem for a bilateral teleoperator scheme is considered. The recently proposed Immersion and Invariance (I&I) observer is used to obtain an exponentially convergent estimate of the unmeasured velocities. Moreover, it is proven that when this observer is interconnected to the nonlinear teleoperator together with a Proportional plus damping (P+d) controller, the overall system is globally stable. Finally, in the case when the human operator and the environment do not exert forces on the local and remote manipulator, respectively, global asymptotic convergence to zero of the velocities and of the position tracking error is achieved. These results are obtained by introducing two important design modifications ensuring the explicit derivation of the observer dynamics and that the interconnected system inherits the same stability properties as in the full-measurement case. The theoretical results are illustrated with simulations using local and remote two degree-of-freedom nonlinear manipulators.

  • A proportional plus damping injection controller for teleoperators with joint fexibility and time¿delays

     Nuño, Emmanuel; Sarras, Ioannis; Basañez Villaluenga, Luis; Kinnaert, Michel
    IEEE International Conference on Robotics and Automation
    Presentation's date: 2012-05-14
    Presentation of work at congresses

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    The problem of controlling a rigid bilateral teleoperator with time-delays has been effectively addressed since the late 80’s. However, the control of flexible joint manipulators in a bilateral teleoperation scenario is still an open problem. In the present paper we report two versions of a proportional plus damping injection controller that are capable of globally stabilizing a nonlinear bilateral teleoperator with joint flexibility and variable time-delays. The first version controls a teleoperator composed by a rigid local manipulator and a flexible joint remote manipulator and the second version deals with local and remote manipulators with joint flexibility. For both schemes, it is proved that the joint and motor velocities and the local and remote position error are bounded. Moreover, if the human operator and remote environment forces are zero then velocities asymptotically converge to zero and position tracking is established. Simulations are presented to show the performance of the proposed controllers.

  • Consensus in networks of nonidentical Euler-Lagrange systems with variable time-delays

     Nuño, Emmanuel; Sarras, Ioannis; Panteley, Elena; Basañez Villaluenga, Luis
    IEEE Conference on Decision and Control
    Presentation's date: 2012-12-10
    Presentation of work at congresses

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    The present work reports a sufficient condition for the consensus of a network of nonidentical Euler-Lagrange (EL) systems with variable time-delays in the communications. The EL-systems are controlled by simple Proportional plus damping (P+d) schemes and the interconnection network is modeled as an undirected weighted graph. Additionally, for the case without delays, the paper reports a new Strict Lyapunov Function (SLF)for the closed-loop system. Experimental evidence, using three 3-Degrees-of-Freedom manipulators interconnected through the Internet, support the theoretical results of this paper.

  • 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
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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
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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.

  • Bilateral teleoperation control without velocity measurements

     Nuño, Emmanuel; Basañez Villaluenga, Luis; Obregón-Pulido, Guillermo; Solís-Perales, Gualberto
    World Congress of the International Federation of Automatic Control
    Presentation's date: 2011-09-01
    Presentation of work at congresses

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    This paper presents two controllers for a nonlinear bilateral teleoperation system that do not rely on velocity measurements. Under the reasonable assumptions that the human operator and the environment define passive maps from force to velocity, both controllers can ensure boundedness of velocities and position error. Moreover, if the human and environment forces are bounded, one of the controllers ensure velocity synchronization and the other velocity convergence to zero. Simulations, comparing the performance on free motion and interacting with a stiff wall, support the performance of the reported schemes.

  • Trajectory tracking and consensus of networks of Euler¿Lagrange systems

     Nuño, Emmanuel; Ortega, Romeo; Basañez Villaluenga, Luis; Hill, David
    World Congress of the International Federation of Automatic Control
    Presentation's date: 2011-09-01
    Presentation of work at congresses

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    This paper addresses the problem of synchronizing networks of nonidentical, nonlinear dynamical systems described by Euler–Lagrange equations. It is assumed that the communication graph is simply connected and that the systems are fully actuated, with their states available for measurement. The communications can be subject to constant time-delays. The main result of the paper is a controller for each system in the network, capable of tracking a desired trajectory and, if such trajectory does not exist, capable of reaching a network consensus. Moreover, it is proved that, if there are no time-delays and the graph is balanced each system reaches a consensus arbitrarily near the average of the initial conditions of all the systems in the network. Simulations using a ten robot manipulator network with different time-delays are provided.

  • Synchronization of networks of nonidentical Euler-Lagrange systems with uncertain parameters and communication delays

     Nuño Ortega, Emmanuel; Ortega, Romeo; Basañez Villaluenga, Luis; Hill, David
    IEEE transactions on automatic control
    Date of publication: 2011-04
    Journal article

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  • Erratum to ``An adaptive controller for nonlinear teleoperators"

     Nuño, Emmanuel; Ortega, Romeo; Basañez Villaluenga, Luis
    Automatica
    Date of publication: 2011-05-01
    Journal article

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  • Passivity-based control for bilateral teleoperation: A tutorial

     Nuño, Emmanuel; Basañez Villaluenga, Luis; Ortega, Romeo
    Automatica
    Date of publication: 2011-03
    Journal article

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    This tutorial revisits several of the most recent passivity-based controllers for nonlinear bilateral teleoperators with guaranteed stability properties. These schemes, which include scattering–based, damping injection and adaptive controllers, ensure asymptotic stability in multiple situations that range from constant to variable time-delays, with or without scattering transformation and with or without position tracking capabilities. Although all controllers exploit the basic property of passivity of the teleoperators, they have been developed invoking various analysis and design tools, which complicates their comparison and relative performance assessment. The objective of this paper is to present a unified theoretical framework—based on a general Lyapunov–like function—that, upon slight modification, allows to analyze the stability of all the schemes.

  • Singularity-invariant leg rearrangements in stewart-gouch platforms

     Borras Sol, Julia
    Defense's date: 2011-04-15
    Institute of Industrial and Control Engineering (IOC), Universitat Politècnica de Catalunya
    Theses

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  • Nonlinear control and geometric constraint enforcement for teleoperated task execution

     Rodriguez Tsouroukdissian, Adolfo; Nuño, Emmanuel; Palomo Avellaneda, Leopold; Basañez Villaluenga, Luis
    IEEE/RSJ International Conference on Intelligent Robots and Systems
    Presentation's date: 2010-10-18
    Presentation of work at congresses

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    This work presents a multimodal teleoperation framework that makes use of novel tools and techniques, such as: nonlinear teleoperators control, for ensuring position tracking in the presence of variable time-delays; relational positioning, for increasing operator performance on precise movement execution by visually and haptically displaying geometric constraints; and augmented reality, for visually combining real and virtual information in a compelling way. Experimental evidence is presented that validates the aptitude of the different components of the proposed framework.

  • Position tracking using adaptive control for bilateral teleoperators with time-delays

     Nuño, Emmanuel; Basañez Villaluenga, Luis; Ortega, Romeo; Obregón-Pulido, Guillermo
    IEEE International Conference on Robotics and Automation
    Presentation's date: 2010-05-03
    Presentation of work at congresses

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    This paper presents two versions of adaptive controllers for nonlinear bilateral teleoperators, each providing asymptotic convergence of velocity and position errors to zero, independent of constant time-delays. Moreover, the proposed schemes do not rely on the use of the scattering transformation. The paper also proves that the teleoperator is Input-to-State Stable from human operator and environment inputs to some synchronization signals. Simulations show the effectiveness of the proposed controllers.

  • Adaptive control for the synchronization of multiple robot manipulators with coupling time-delays

     Nuño, Emmanuel; Basañez Villaluenga, Luis; Ortega, Romeo
    IEEE/RSJ International Conference on Intelligent Robots and Systems
    Presentation's date: 2010-10-18
    Presentation of work at congresses

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    Two controllers capable of achieving asymptotic convergence of position and velocity errors, of the ithmanipulator within a multiple robot network, are proposed. The controllers employ adaptive techniques to find an estimate of the physical parameters of the nonlinear dynamics of the robot network. Moreover, the controllers can deal with different connectivity topologies (ring and star) and and can handle timedelays in the communications. Simulations, using a ten robot manipulators network with different connectivity topologies, that confirm the theoretical results are presented.

  • An adaptive controller for nonlinear teleoperators

     Nuño Ortega, Emmanuel; Ortega, Romeo; Basañez Villaluenga, Luis
    Automatica
    Date of publication: 2010-01
    Journal article

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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.

  • Comité Español de Automática

     Basañez Villaluenga, Luis
    Award or recognition

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  • 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
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  • A Framework for the simulation and haptic display of dynamic systems subject to holonomic constraints

     Rodriguez Tsouroukdissian, Adolfo; Basañez Villaluenga, Luis; Colgate, Edward; Faulring, Eric L.
    International journal of robotics research
    Date of publication: 2010-04
    Journal article

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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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  • Nonlinear Bilateral Teleoperation: Stability Analysis

     Nuño Ortega, Emmanuel; Basañez Villaluenga, Luis
    IEEE International conference on robotics and automation
    Date of publication: 2009
    Journal article

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  • Asymptotic Stability of Teleoperators with Variable Time-Delays

     Nuño Ortega, Emmanuel; Basañez Villaluenga, Luis; Prada Sarasola, Miguel
    IEEE International conference on robotics and automation
    Date of publication: 2009
    Journal article

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  • Relational Positioning in Robot Task Specification and Execution.

     Rodriguez Tsouroukdissian, Adolfo
    Defense's date: 2009-07-16
    Institute of Industrial and Control Engineering (IOC), Universitat Politècnica de Catalunya
    Theses

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  • Teleoperation

     Basañez Villaluenga, Luis; Suarez Feijoo, Raul
    Date of publication: 2009
    Book chapter

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  • 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
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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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  • Control of Teleoperators with Time-Delay: A Lyapunov Approach

     Nuño Ortega, Emmanuel; Basañez Villaluenga, Luis; Ortega, Romeo
    Lecture notes in control and information sciences
    Date of publication: 2009
    Journal article

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  • Position Tracking for Non-linear Teleoperators with Variable Time Delay

     Nuño Ortega, Emmanuel; Basañez Villaluenga, Luis; Spong, MW
    International journal of robotics research
    Date of publication: 2009-07
    Journal article

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  • Validation of an Aided Teleoperation Framework for Robotic Tasks

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    40TH INTERNATIONAL SYMPOSIUM ON ROBOTICS
    Presentation of work at congresses

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  • A new proportional controller for onlinear bilateral teoperators

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    World Congress of the International Federation of Automatic Control
    Presentation of work at congresses

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